global variables in Ruby and the 'english' extension

gistfile1.rb

>> global_variables
=> [:$;, :$-F, :$@, :$!, :$SAFE, :$~, :$&, :$`, :$', :$+, :$=, :$KCODE, :$-K, :$,, :$/, :$-0, 
:$\, :$_, :$stdin, :$stdout, :$stderr, :$>, :$<, :$., :$FILENAME, :$-i, :$*, :$?, :$$, :$:, 
:$-I, :$LOAD_PATH, :$", :$LOADED_FEATURES, :$VERBOSE, :$-v, :$-w, :$-W, :$DEBUG, :$-d, :$0, 
:$PROGRAM_NAME, :$-p, :$-l, :$-a, :$binding, :$1, :$2, :$3, :$4, :$5, :$6, :$7, :$8, :$9]

>> require 'english'
=> true

>> global_variables
=> [:$;, :$-F, :$@, :$!, :$SAFE, :$~, :$&, :$`, :$', :$+, :$=, :$KCODE, :$-K, :$,, :$/, :$-0, 
:$\, :$_, :$stdin, :$stdout, :$stderr, :$>, :$<, :$., :$FILENAME, :$-i, :$*, :$?, :$$, :$:, 
:$-I, :$LOAD_PATH, :$", :$LOADED_FEATURES, :$VERBOSE, :$-v, :$-w, :$-W, :$DEBUG, :$-d, :$0, 
:$PROGRAM_NAME, :$-p, :$-l, :$-a, :$binding, :$ERROR_INFO, :$ERROR_POSITION, :$FS, 
:$FIELD_SEPARATOR, :$OFS, :$OUTPUT_FIELD_SEPARATOR, :$RS, :$INPUT_RECORD_SEPARATOR, :$ORS, 
:$OUTPUT_RECORD_SEPARATOR, :$INPUT_LINE_NUMBER, :$NR, :$LAST_READ_LINE, :$DEFAULT_OUTPUT, 
:$DEFAULT_INPUT, :$PID, :$PROCESS_ID, :$CHILD_STATUS, :$LAST_MATCH_INFO, :$IGNORECASE, 
:$ARGV, :$MATCH, :$PREMATCH, :$POSTMATCH, :$LAST_PAREN_MATCH, 
:$1, :$2, :$3, :$4, :$5, :$6, :$7, :$8, :$9]