íta noun "a flash" (PM:363)
Sindarin
aglan
noun. ray of light
agol
noun. flash
Quenya
alca
ray of light
íta
flash
íta
noun. flash, flash, *lightning
A noun for “a flash” appearing in The Shibboleth of Fëanor as part of a discussion the name Q. Itarillë, S. Idril from the late 1960s, derived from the root √IT (PM/363). It seems to be a bright and direct flash of light, as opposed to ᴹQ. tinde “glint” for a less brilliant and reflected flash of light.
Neo-Quenya: As a flash of light, this word might also be used for “✱lightning” and on this basis used for Neo-Quenya words having to do with electricity.
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
agla
noun. flash
A noun in the Gnomish Lexicon of the 1910s given as G. agla “flash” (GL/42); Tolkien made a point that it was not connected to G. augla “ray of sunlight, sunbeam” (GL/20), and thus it was likely derived from the early root ᴱ√KALA (QL/44). In the Gnomish Lexicon Slips it was revised from {aglan or agl >>} aglen “a flash” (PE13/108). In Early Noldorin Word-lists of the 1920s this became {aglen >>} ᴱN. aglann “ray of light” (PE13/136, 158).
Neo-Sindarin: I think this word can be adapted to Neo-Sindarin as ᴺS. agol “flash”, where the -ol is the usual result of a syllabified final l: ✱agl(a) > agḷ > agol. I would adapt the pre-revision Gnomish form because I think the Early Noldorin form is better as ᴺS. aglan “ray of light”, and agol also happens to compatible with early 1950s ✶ak’la- “shine out, flash” (PE18/87).
aglen
noun. flash
Early Noldorin
aglann
noun. ray of light
A noun appearing as ᴱN. {aglen >>} aglann “ray of light” in the Early Noldorin Word Lists of the 1910s (PE13/136, 158), probably derived from the early root ᴱ√KALA (QL/44). It may be related to G. {aglan >>} aglen “a flash” appearing in Gnomish Lexicon Slips (PE13/108), and perhaps replaced G. augla “ray of sunlight, sunbeam” (GL/20), though this last word appears to be derived from ᴱ√AWA “burn; be parched, yellow, warm” (QL/33).
Neo-Sindarin: I think this word can be adapted into Neo-Sindarin as ᴺS. aglan “ray of light”, related to ᴹQ. alka of the same meaning.
Qenya
alka
noun. ray of light, ray of light, [ᴱQ.] light of day; shining
A word for “ray of light” in The Etymologies of the 1930s derived from the root ᴹ√AKLA-R (Ety/AKLA-R).
Conceptual Development: ᴱQ. alka “ray” appeared in the Qenya Lexicon of the 1910s as a derivative of the early root ᴱ√ḶKḶ; its primitive form ᴱ✶ak’lā indicated a historical development similar to that of The Etymologies (QL/30). The phrase ᴱQ. alkarissen oilimain “in the last rays of light” appeared in some of the versions of the Oilima Markirya poem from around 1930 (MC/221), but here the form was alkar as in alkar-issen = “ray-(locative-plural)”. The word alkar appeared in one of the glossaries of Oilima Markirya drafts with the translation “shining, light of day” (PE16/75). By The Etymologies of the 1930s, however, the form and meaning seem to have reverted to alka “ray of light” (see above).
alca ("k")noun "ray of light" (AKLA-R)