Antonyms of adj infantile

2 of 3 senses of infantile

Sense 1
childish, infantile -- (indicating a lack of maturity; "childish tantrums"; "infantile behavior")

INDIRECT (VIA immature) -> mature -- (characteristic of maturity; "mature for her age")

Sense 3
infantile -- (being or befitting or characteristic of an infant; "infantile games")

INDIRECT (VIA young) -> old -- ((used especially of persons) having lived for a relatively long time or attained a specific age; "his mother is very old"; "a ripe old age"; "how old are you?")

Similarity of adj infantile

3 senses of infantile

Sense 1
childish, infantile -- (indicating a lack of maturity; "childish tantrums"; "infantile behavior")
       => immature (vs. mature) -- (characteristic of a lack of maturity; "immature behavior")

Sense 2
infantile -- (of or relating to infants or infancy; "infantile paralysis")

Sense 3
infantile -- (being or befitting or characteristic of an infant; "infantile games")
       => young (vs. old), immature -- ((used of living things especially persons) in an early period of life or development or growth; "young people")