Antonyms of adj kittenish

1 sense of kittenish

Sense 1
kittenish, frisky -- (playful like a lively kitten)

INDIRECT (VIA playful) -> unplayful, serious, sober -- (completely lacking in playfulness)

Similarity of adj kittenish

1 sense of kittenish

Sense 1
kittenish, frisky -- (playful like a lively kitten)
       => playful (vs. unplayful) -- (full of fun and high spirits; "playful children just let loose from school")