An adjective in the Gnomish Lexicon of the 1910s appearing as G. helon “frozen”, an adjectival form and possibly a passive participle of G. hel- “freeze” (GL/48).
Neo-Sindarin: For purposes of Neo-Sindarin, I think it is best to update this to the Sindarin passive-participle form ᴺS. hellen “frozen”.
halcin ("k") adj. "frozen" (LT1:254)