diff --git a/docs/reference/inheritance.txt b/docs/reference/inheritance.txt
index dcba02a96..240647702 100644
--- a/docs/reference/inheritance.txt
+++ b/docs/reference/inheritance.txt
@@ -32,7 +32,7 @@ fields, associations, validations and scopes are copied to the child document.
 
    class Browser < Canvas
      field :version, type: Integer
-     scope :recent, ->{ where(:version.gt => 3) }
+     scope :recent, ->{ gt(version: 3) }
    end
 
    class Firefox < Browser
diff --git a/docs/reference/map-reduce.txt b/docs/reference/map-reduce.txt
index 2251ffa91..025423d2a 100644
--- a/docs/reference/map-reduce.txt
+++ b/docs/reference/map-reduce.txt
@@ -48,7 +48,7 @@ functions.
     }
   }
 
-  Band.where(:likes.gt => 100).map_reduce(map, reduce).out(inline: 1)
+  Band.gt(likes: 100).map_reduce(map, reduce).out(inline: 1)
 
 Just like criteria, map/reduce calls are lazily evaluated. So nothing will
 hit the database until you iterate over the results, or make a call on the
@@ -80,7 +80,7 @@ or its aliases ``raw`` and ``results``:
 
 .. code-block:: ruby
 
-  mr = Band.where(:likes.gt => 100).map_reduce(map, reduce).out(inline: 1)
+  mr = Band.gt(likes: 100).map_reduce(map, reduce).out(inline: 1)
 
   mr.execute
   # => {"results"=>[{"_id"=>"Tool", "value"=>{"likes"=>200.0}}],
@@ -111,7 +111,7 @@ The following code illustrates retrieving the statistics:
 
 .. code-block:: ruby
 
-  mr = Band.where(:likes.gt => 100).map_reduce(map, reduce).out(inline: 1)
+  mr = Band.gt(likes: 100).map_reduce(map, reduce).out(inline: 1)
 
   mr.counts
   # => {"input"=>4, "emit"=>4, "reduce"=>1, "output"=>1}
diff --git a/docs/reference/queries.txt b/docs/reference/queries.txt
index 8dcae9b27..746cea97a 100644
--- a/docs/reference/queries.txt
+++ b/docs/reference/queries.txt
@@ -23,7 +23,7 @@ A more complex query utilizing various Mongoid features could be as follows:
 .. code-block:: ruby
 
   Band.
-    where(:founded.gte => "1980-01-01").
+    gte(founded: "1980-01-01").
     in(name: [ "Tool", "Deftones" ]).
     union.
     in(name: [ "Melvins" ])
@@ -59,14 +59,14 @@ Criteria instance with the new conditions added to the existing conditions:
 
 .. code-block:: ruby
 
-  scope = Band.where(:founded.gte => "1980-01-01")
+  scope = Band.gte(founded: "1980-01-01")
   # => #<Mongoid::Criteria
   #   selector: {"founded"=>{"$gte"=>"1980-01-01"}}
   #   options:  {}
   #   class:    Band
   #   embedded: false>
 
-  scope.where(:founded.lte => "2020-01-01")
+  scope.lte(founded: "2020-01-01")
   # => #<Mongoid::Criteria
   #   selector: {"founded"=>{"$gte"=>"1980-01-01", "$lte"=>"2020-01-01"}}
   #   options:  {}
@@ -156,6 +156,12 @@ An MQL operator may be specified on any field using the hash syntax:
 Symbol Operator Syntax
 ----------------------
 
+.. warning::
+
+  Symbol operator syntax is deprecated and will be extracted to a gem
+  in Mongoid 10. It is strongly recommended to switch to either
+  field syntax or MQL syntax as shown above.
+
 MQL operators may be specified as methods on symbols for the respective field
 name, as follows:
 
diff --git a/docs/release-notes/mongoid-9.0.txt b/docs/release-notes/mongoid-9.0.txt
index 8a32c94a6..a69f572e9 100644
--- a/docs/release-notes/mongoid-9.0.txt
+++ b/docs/release-notes/mongoid-9.0.txt
@@ -127,6 +127,35 @@ Deprecated functionality removed
   definitions without replacement.
 
 
+Symbol query operator syntax deprecated
+---------------------------------------
+
+The following query syntax which monkey-patches the Symbol class is
+deprecated as of Mongoid 9. It will be removed in Mongoid 10.
+
+.. code-block:: ruby
+
+  # Deprecated symbol operator query syntax
+  Band.where(:founded.gt => 1980)
+
+Please replace this syntax with one of the following:
+
+.. code-block:: ruby
+
+  # Field query syntax
+  Band.gt(founded: 1980)
+
+  # MQL query syntax
+  Band.where(founded: { '$gt' => 1980 })
+
+Note that the above syntaxes can equivalently do everything
+the symbol operator syntax can.
+
+Although we strongly recommend to migrate your code,
+if you would like to continue using the deprecated syntax,
+please add the 'mongoid-symbol-operators' gem to your Gemfile.
+
+
 ``touch`` method now clears changed state
 -----------------------------------------
 
diff --git a/lib/mongoid/criteria/queryable/extensions/symbol.rb b/lib/mongoid/criteria/queryable/extensions/symbol.rb
index dd195e3ba..d8fb7d31e 100644
--- a/lib/mongoid/criteria/queryable/extensions/symbol.rb
+++ b/lib/mongoid/criteria/queryable/extensions/symbol.rb
@@ -22,23 +22,6 @@ def __expr_part__(value, negating = false)
           end
 
           module ClassMethods
-
-            # Adds a method on symbol as a convenience for the MongoDB operator.
-            #
-            # @example Add the $in method.
-            #   Symbol.add_key(:in, "$in")
-            #
-            # @param [ Symbol ] name The name of the method.
-            # @param [ Symbol ] strategy The name of the merge strategy.
-            # @param [ String ] operator The MongoDB operator.
-            # @param [ String ] additional The additional MongoDB operator.
-            def add_key(name, strategy, operator, additional = nil, &block)
-              define_method(name) do
-                method = :"__#{strategy}__"
-                Key.new(self, method, operator, additional, &block)
-              end
-            end
-
             # Evolves the symbol into a MongoDB friendly value - in this case
             # a symbol.
             #
diff --git a/lib/mongoid/criteria/queryable/macroable.rb b/lib/mongoid/criteria/queryable/macroable.rb
index acb76d797..995367b81 100644
--- a/lib/mongoid/criteria/queryable/macroable.rb
+++ b/lib/mongoid/criteria/queryable/macroable.rb
@@ -17,9 +17,87 @@ module Macroable
         # @param [ Symbol ] strategy The merge strategy.
         # @param [ String ] operator The MongoDB operator.
         # @param [ String ] additional The additional MongoDB operator.
-        def key(name, strategy, operator, additional = nil, &block)
-          ::Symbol.add_key(name, strategy, operator, additional, &block)
+        #
+        # @deprecated Will be moved to the mongoid-symbol-operators gem.
+        def define_key(name, strategy, operator, additional = nil, &block)
+          warning_name = :"symbol_selector_#{name}_deprecated"
+
+          Mongoid::Warnings.warning warning_name,
+                                    "The query selector method Symbol##{name} is deprecated and " \
+                                    "will be removed in Mongoid 10. Please use either Criteria##{name}, " \
+                                    "the #{operator} operator, or add gem 'mongoid-symbol-operators' " \
+                                    'to your Gemfile.'
+
+          ::Symbol.define_method(name) do
+            Mongoid::Warnings.send(:"warn_#{warning_name}") unless selectors_gem_present?
+            Mongoid::Criteria::Queryable::Key.new(self, :"__#{strategy}__", operator, additional, &block)
+          end
+        end
+
+        def selectors_gem_present?
+          return @selectors_gem_present if defined?(@selectors_gem_present)
+
+          @selectors_gem_present = !defined?(Bundler) ||
+                                   !!Gem::Specification.find_by_name('mongoid-symbol-operators')
+        end
+
+        define_key :all, :union, '$all'
+
+        define_key :elem_match, :override, '$elemMatch'
+
+        define_key :exists, :override, '$exists' do |value|
+          Mongoid::Boolean.evolve(value)
         end
+
+        define_key :eq, :override, '$eq'
+
+        define_key :gt, :override, '$gt'
+
+        define_key :gte, :override, '$gte'
+
+        define_key :in, :intersect, '$in'
+
+        define_key :lt, :override, '$lt'
+
+        define_key :lte, :override, '$lte'
+
+        define_key :mod, :override, '$mod'
+
+        define_key :ne, :override, '$ne'
+
+        define_key :near, :override, '$near'
+
+        define_key :near_sphere, :override, '$nearSphere'
+
+        define_key :nin, :intersect, '$nin'
+
+        define_key :not, :override, '$not'
+
+        define_key :with_type, :override, '$type' do |value|
+          ::Integer.evolve(value)
+        end
+
+        define_key :with_size, :override, '$size' do |value|
+          ::Integer.evolve(value)
+        end
+
+        define_key :intersects_line, :override, '$geoIntersects', '$geometry' do |value|
+          { 'type' => Mongoid::Criteria::Queryable::Selectable::LINE_STRING, 'coordinates' => value }
+        end
+
+        define_key :intersects_point, :override, '$geoIntersects', '$geometry' do |value|
+          { 'type' => Mongoid::Criteria::Queryable::Selectable::POINT, 'coordinates' => value }
+        end
+
+        define_key :intersects_polygon, :override, '$geoIntersects', '$geometry' do |value|
+          { 'type' => Mongoid::Criteria::Queryable::Selectable::POLYGON, 'coordinates' => value }
+        end
+
+        define_key :within_polygon, :override, '$geoWithin', '$geometry' do |value|
+          { 'type' => Mongoid::Criteria::Queryable::Selectable::POLYGON, 'coordinates' => value }
+        end
+
+        define_key :within_box, :override, '$geoWithin', '$box'
       end
     end
   end
diff --git a/lib/mongoid/criteria/queryable/selectable.rb b/lib/mongoid/criteria/queryable/selectable.rb
index cc4e86a20..f358e0768 100644
--- a/lib/mongoid/criteria/queryable/selectable.rb
+++ b/lib/mongoid/criteria/queryable/selectable.rb
@@ -8,7 +8,6 @@ module Queryable
       # document from the database. The selectable module brings all functionality
       # to the selectable that has to do with building MongoDB selectors.
       module Selectable
-        extend Macroable
 
         # Constant for a LineString $geometry.
         LINE_STRING = 'LineString'
@@ -54,7 +53,6 @@ def all(*criteria)
           end.reset_strategies!
         end
         alias_method :all_in, :all
-        key :all, :union, '$all'
 
         # Add the $and criterion.
         #
@@ -142,7 +140,6 @@ def elem_match(criterion)
 
           and_with_operator(criterion, '$elemMatch')
         end
-        key :elem_match, :override, '$elemMatch'
 
         # Add the $exists selection.
         #
@@ -165,9 +162,6 @@ def exists(criterion)
             Mongoid::Boolean.evolve(value)
           end
         end
-        key :exists, :override, '$exists' do |value|
-          Mongoid::Boolean.evolve(value)
-        end
 
         # Add a $geoIntersects or $geoWithin selection. Symbol operators must
         # be used as shown in the examples to expand the criteria.
@@ -209,20 +203,6 @@ def geo_spatial(criterion)
           __merge__(criterion)
         end
 
-        key :intersects_line, :override, '$geoIntersects', '$geometry' do |value|
-          { 'type' => LINE_STRING, 'coordinates' => value }
-        end
-        key :intersects_point, :override, '$geoIntersects', '$geometry' do |value|
-          { 'type' => POINT, 'coordinates' => value }
-        end
-        key :intersects_polygon, :override, '$geoIntersects', '$geometry' do |value|
-          { 'type' => POLYGON, 'coordinates' => value }
-        end
-        key :within_polygon, :override, '$geoWithin', '$geometry' do |value|
-          { 'type' => POLYGON, 'coordinates' => value }
-        end
-        key :within_box, :override, '$geoWithin', '$box'
-
         # Add the $eq criterion to the selector.
         #
         # @example Add the $eq criterion.
@@ -239,7 +219,6 @@ def eq(criterion)
 
           and_with_operator(criterion, '$eq')
         end
-        key :eq, :override, '$eq'
 
         # Add the $gt criterion to the selector.
         #
@@ -257,7 +236,6 @@ def gt(criterion)
 
           and_with_operator(criterion, '$gt')
         end
-        key :gt, :override, '$gt'
 
         # Add the $gte criterion to the selector.
         #
@@ -275,7 +253,6 @@ def gte(criterion)
 
           and_with_operator(criterion, '$gte')
         end
-        key :gte, :override, '$gte'
 
         # Adds the $in selection to the selectable.
         #
@@ -307,7 +284,6 @@ def in(condition)
           end
         end
         alias_method :any_in, :in
-        key :in, :intersect, '$in'
 
         # Add the $lt criterion to the selector.
         #
@@ -325,7 +301,6 @@ def lt(criterion)
 
           and_with_operator(criterion, '$lt')
         end
-        key :lt, :override, '$lt'
 
         # Add the $lte criterion to the selector.
         #
@@ -343,7 +318,6 @@ def lte(criterion)
 
           and_with_operator(criterion, '$lte')
         end
-        key :lte, :override, '$lte'
 
         # Add a $maxDistance selection to the selectable.
         #
@@ -376,7 +350,6 @@ def mod(criterion)
 
           and_with_operator(criterion, '$mod')
         end
-        key :mod, :override, '$mod'
 
         # Adds $ne selection to the selectable.
         #
@@ -395,7 +368,6 @@ def ne(criterion)
           and_with_operator(criterion, '$ne')
         end
         alias_method :excludes, :ne
-        key :ne, :override, '$ne'
 
         # Adds a $near criterion to a geo selection.
         #
@@ -413,7 +385,6 @@ def near(criterion)
 
           and_with_operator(criterion, '$near')
         end
-        key :near, :override, '$near'
 
         # Adds a $nearSphere criterion to a geo selection.
         #
@@ -431,7 +402,6 @@ def near_sphere(criterion)
 
           and_with_operator(criterion, '$nearSphere')
         end
-        key :near_sphere, :override, '$nearSphere'
 
         # Adds the $nin selection to the selectable.
         #
@@ -463,7 +433,6 @@ def nin(condition)
           end
         end
         alias_method :not_in, :nin
-        key :nin, :intersect, '$nin'
 
         # Adds $nor selection to the selectable.
         #
@@ -526,7 +495,6 @@ def not(*criteria)
             end
           end
         end
-        key :not, :override, '$not'
 
         # Negate the arguments, constraining the query to only those documents
         # that do NOT match the arguments.
@@ -668,9 +636,6 @@ def with_size(criterion)
             ::Integer.evolve(value)
           end
         end
-        key :with_size, :override, '$size' do |value|
-          ::Integer.evolve(value)
-        end
 
         # Adds a $type selection to the selectable.
         #
@@ -692,9 +657,6 @@ def with_type(criterion)
             ::Integer.evolve(value)
           end
         end
-        key :with_type, :override, '$type' do |value|
-          ::Integer.evolve(value)
-        end
 
         # Construct a text search selector.
         #