Kittenishness refers to the playful or flirty behavior exhibited by a young cat or a woman. Its antonyms include seriousness, maturity, sobriety, sedateness, gravity, solemnity, and wisdom. Seriousness denotes an absence of frivolity or purposeless playfulness, while maturity means acting in a sensible and responsible way. Sobriety suggests a lack of frivolousness or addiction, while sedateness and gravity imply a calm, composed demeanor. Solemnity signifies a serious and formal attitude, while wisdom suggests a thoughtful, discerning approach to life. Overall, the antonyms for kittenishness encompass a range of qualities that are more mature, somber, and reserved than playful and flirtatious.