calm × windy, troubled

capable × incapable

careful × careless

cheap × expensive

cheerful × sad, discouraged, dreary

clear × cloudy, opaque

clever × stupid

clockwise × counterclockwise

close × far, distant

closed × open

cold × hot

combine × separate

come × go

comfort × discomfort

common × rare

contract × expand

cool × warm

correct × incorrect, wrong

courage × cowardice

create × destroy

crooked × straight

cruel × kind

compulsory × voluntary

courteous × discourteous, rude