A verb in the Qenya Lexicon of the 1910s appearing as ᴱQ. hilkin “it freezes” based on the early root ᴱ√HḶKḶ, a variant of ᴱ√HELE (QL/39).

Neo-Quenya: Since there is no sign of ᴱ√HḶKḶ in Tolkien’s later writings, I think it is best is adapt this verb as ᴺQ. hel- “freeze” based directly on the later root √KHEL of ice words. Since the root is ice-related, I’d limit the meaning of this verb to the freezing of water and similar substances. For freezing weather, I’d use Q. nicu-.