Gnomish
ganthan
adjective. waxen, grown big, grown up, adult, [originally?] large
Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
The word G. {gantha >>} ganthan “(large), waxen, grown big, grown up, adult” appeared in the Gnomish Lexicon of the 1910s based on G. gant “larger” (GL/37). I believe the parenthetical “(large)” indicates its ancient meaning and “waxen, grown big, grown up, adult” is its modern meaning.
Neo-Sindarin: Since I retain ᴺS. gant for purposes of Neo-Sindarin as a derivative of the Neo-Root ᴺ√GYANTA, I would retain and adapt its enlargement as ᴺS. gannan “waxen, grown big, grown up, adult”, originally just “†large”.