Quiescency refers to a state of being still, quiet, and inactive. Some common antonyms for this word include activity, movement, and restlessness. These words represent the opposite of quiescency and imply a sense of constant motion or activity. Another antonym for quiescency is agitation, which suggests a state of extreme restlessness or irritation. In contrast, serenity and calmness can be considered synonyms for quiescency. These words suggest a state of peacefulness and tranquillity. Other antonyms for quiescency include energy, action, and liveliness, which all imply a sense of being active and lively.