typos rectified lifecycle => life cycle

activemodel/lib/active_model/validator.rb

@@ -61,7 +61,7 @@ module ActiveModel
   #   end
   #
   # Note that the validator is initialized only once for the whole application
-  # lifecycle, and not on each validation run.
+  # life cycle, and not on each validation run.
   #
   # The easiest way to add custom validators for validating individual attributes
   # is with the convenient <tt>ActiveModel::EachValidator</tt>.

activesupport/lib/active_support/callbacks.rb

@@ -7,14 +7,14 @@
 require 'thread'
 
 module ActiveSupport
-  # Callbacks are code hooks that are run at key points in an object's lifecycle.
+  # Callbacks are code hooks that are run at key points in an object's life cycle.
   # The typical use case is to have a base class define a set of callbacks
   # relevant to the other functionality it supplies, so that subclasses can
   # install callbacks that enhance or modify the base functionality without
   # needing to override or redefine methods of the base class.
   #
   # Mixing in this module allows you to define the events in the object's
-  # lifecycle that will support callbacks (via +ClassMethods.define_callbacks+),
+  # life cycle that will support callbacks (via +ClassMethods.define_callbacks+),
   # set the instance methods, procs, or callback objects to be called (via
   # +ClassMethods.set_callback+), and run the installed callbacks at the
   # appropriate times (via +run_callbacks+).
@@ -648,7 +648,7 @@ def reset_callbacks(name)
         self.set_callbacks name, callbacks.dup.clear
       end
 
-      # Define sets of events in the object lifecycle that support callbacks.
+      # Define sets of events in the object life cycle that support callbacks.
       #
       #   define_callbacks :validate
       #   define_callbacks :initialize, :save, :destroy

guides/source/active_record_callbacks.md

@@ -55,7 +55,7 @@ class User < ActiveRecord::Base
 end
 ```
 
-Callbacks can also be registered to only fire on certain lifecycle events:
+Callbacks can also be registered to only fire on certain life cycle events:
 
 ```ruby
 class User < ActiveRecord::Base