Antonyms for the word "protraction" include "retraction," "withdrawal," and "retreat." All of these words describe a pulling back or reeling in rather than a forward movement. "Retraction" specifically refers to the act of drawing something back or retracting it, while "withdrawal" can be used more broadly to describe removing oneself or something else from a situation. "Retreat" implies a purposeful movement away from a location or objective. These antonyms can be used to describe actions that are different from the deliberate, extended movement forward that "protraction" connotes.