sanga (þ) noun "crowd, press, throng" (STAG, SA:thang, LT2:342; pl. sangar (?) twice in Narqelion). In Sangahyando (þ) masc. name "Throng-cleaver", name of a man in Gondor _(SA:thang; a footnote in Letters:425 explains that "throng" here means a closely formed body of enemy soldiers. In the Etymologies, stems STAG, SYAD, _sangahyando is said to be a swordname, and LT2:342 likewise defines the word as a name of Turambar's sword: "cleaver of throngs, Throng-cleaver".)
Quenya
sanga
noun. throng, press, pressure, press, pressure; throng, [ᴹQ.] crowd, pack; [ᴱQ.] tight mass; [ᴹQ.] crowded, packed
sanga
crowd, press, throng
sanga
crowded, packed; pack, throng
sangië
necessity
#sangië (evidently þ, cf. sanga above) noun "necessity" (evidently in the sense of *"tribulation, pressure"; compare sanga, of which #sangië is an abstract formation). Isolated from sangiessemman "in our necessities" (VT44:8)
hyanda
noun. throng
throng, crowd, pressed mass
rimbë
crowd, host, great number
rimbë noun "crowd, host, great number" (RIM, SA:rim, Letters:282)
This word had a lengthy history in Tolkien’s writings, most notably as an element in Sangahyando “Throng-Cleaver”. It first appeared in the Qenya Lexicon of the 1910s as ᴱQ. sanga “throng, tight mass, crowd” under the early root ᴱ√SAŊA (QL/81). It reappeared in the Declension of Nouns (DN) of the early 1930s with the gloss “throng” (PE21/32) and in another slightly later chart with the gloss “crowd” (PE21/42). In The Etymologies from around 1937 it was ᴹQ. sanga “crowd, throng, press” derived from ᴹ√stangā under the root ᴹ✶STAG “press, compress” (Ety/STAG).
In the Quenya Verbal System from 1948 it had an adjectival sense “crowded, packed” along with the noun sense “pack, throng” (PE22/107). It reappeared in Tolkien’s later writings with glosses like “press, pressure, throng” (PE17/116), and in a footnote to a 1972 letter to Richard Jeffery, Tolkien said it could refer to “a closely formed body of enemy soldiers” (Let/425).
Neo-Quenya: For purposes of Neo-Quenya, I would assume the basic noun sense of sanga is a “tight mass”, usable abstractly for a “press” or “pressure”, or for a tightly packed group of people or animals such as “throng, crowd, pack”. I would also it as an adjective meaning “crowded” or “packed”, such as sanga sambe “a packed room”.