Quenya 

nixë

noun. frost; ice-flake or snow-flake

A noun in the Quendi and Eldar essay from 1959-60 glossed “frost” (WJ/417). It also appeared in some etymological notes from around 1959 as a variant of niquis “ice-flake or snowflake” under the root √NIK(W) (PE17/168).

Conceptual Development: The word for “frost” was ᴹQ. helor in the Declension of Nouns of the early 1930s and ᴹQ. helle in The Etymologies of the mid-to-late 1930s, both based on the short root ᴹ√KHEL “freeze” (Ety/KHEL). In The Etymologies Tolkien deleted this short root and its derivatives, retaining only longer ᴹ√KHELEK, and in later writings Tolkien seems to have decided “frost” was based on √NIK(W) instead.

Neo-Quenya: For purposes of Neo-Quenya, I’d limit nixë to “frost” and use niquis for “snowflake” to help differentiate the two words.

Quenya [PE17/168; WJ/417] Group: Eldamo. Published by

nixë

frost

nixë noun "frost" (WJ:417); previously described as a synonym of niquis "ice-flake or snowflake", q.v. (PE17:168)

Sindarin 

nich

noun. frost

A neologism for “frost”, cognate of Q. nixë of the same meaning (WJ/417), that assumes a phonetic development similar to that of S. ach vs. Q. akse (axë) “neck” (PE17/92); see the entry on how [[os|[p], [t], [k] spirantalized before [s]]] in (Old) Sindarin.

Sindarin Group: Eldamo - neologism/reconstructions. Published by

hell

9j¸$ noun. frost

Sindarin [Etymologies] Group: Subject of debate. Published by

Noldorin 

hell

noun. frost

A noun in The Etymologies of the 1930s glossed “frost” derived from the root ᴹ√KHEL “freeze”, but Tolkien deleted this short root and its derivatives, keeping only the longer form ᴹ√KHELEK (Ety/KHEL).

Conceptual Development: The Gnomish Lexicon of the 1910s had a number of similar “frost” related words: G. heloth “frost”, G. hîl {“ice-cold, icy” >>} “frost” as well as G. helfileg “frost on panes, etc.” (GL/48-49), all based on the early root ᴱ√HELE “freeze”, the last with the added element G. fileg “fern”.

Neo-Sindarin: Tolkien probably deleted N. hell “frost” because he abandoned the short root ᴹ√KHEL, but short √KHEL did reappear in later writings (PE17/116), so it is tempting to restore hell “frost” as well. However, this conflicts with other attested words like N. hell “naked”, so I think it is better to use a neologism like ᴺS. nich for “frost”; see that entry for discussion.

Noldorin [Ety/KHEL] Group: Eldamo. 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!

Gnomish

heloth

noun. frost

Gnomish [GL/48; GL/49; LT1A/Helkar] Group: Eldamo. Published by

hîl

noun. frost

Qenya 

helle

noun. frost

helor

noun. frost

nis

noun. minnow, ‘little fish’