Quenya 

nessima

youthful

nessima adj. "youthful" (NETH)

Sindarin 

gwineb

adjective. youthful

Elements

WordGloss
gwîn“youth”
Sindarin Group: Eldamo - neologism/reconstructions. Published by

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!

Qenya 

nessima

adjective. youthful

Elements

WordGloss
nesse“youth”
-ima“able to be done, -able, -ible”

Gnomish

ganothrin

adjective. youthful