Antonyms for the word "antsiness," which refers to a state of restlessness and impatience, could include terms like serenity, calmness, tranquility, poise, composure, and serenity. These are all words that connote a sense of inner peace and quietude, rather than the frenzied energy and agitation that goes along with "antsiness." Some other possible antonyms might include words like patience, equanimity, cool-headedness, moderation, and detachment, all of which imply a certain sense of reserve and self-control that is lacking in someone who is feeling "antsy" or agitated.