Antonyms of adj middle-aged

1 sense of middle-aged

Sense 1
middle-aged -- (being roughly between 45 and 65 years old)

INDIRECT (VIA old) -> young, immature -- ((used of living things especially persons) in an early period of life or development or growth; "young people")

Similarity of adj middle-aged

1 sense of middle-aged

Sense 1
middle-aged -- (being roughly between 45 and 65 years old)
       => old (vs. young) -- ((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?")