Wiktionary
subadult
a. not yet adult. alt. not yet adult. n. A person who, or animal that, is not yet an adult.
Usage examples of "subadult".
He greeted the dragon as Baken had shown him, as an adult greeted a subadult, with a breathy trill and a head bump, then without a pause, he vaulted up into the saddle.
The fresh clothing she wore came from the Speaker's subadult children, who were faddishly fond of certain kinds of human garb.
The males, weanlings up to subadult, they're in an isolation facility.