Yón (1) noun "Son" (VT44:12, 17, referring to Jesus. Tolkien rewrote the text in question. Normally the Quenya word for "son" appears as yondo, which also refers to Jesus in one text.)
Quenya
yo-
prefix. together (of three or more things)
Yón
son
anon
son
anon noun "son" (PE17:170), possibly intended by Tolkien as a replacement for yondo.
anon
noun. son
A transient word for “son” in Notes on Names (NN) from 1957, written of above the more common yon-do (PE17/170).
vó
son
vó (actually spelt vô), also vondo, noun "son" (LT2:336; in Tolkien's later Quenya yondo)
yondo
son
yondo noun "son" (YŌ/YON, VT43:37); cf. yonya and the patronymic ending -ion. Early "Qenya" has yô, yond-, yondo "son" (LT2:342). According to LT2:344, these are poetic words, but yondo seems to be the normal word for "son" in LotR-style Quenya. Yón appears in VT44, 17, but Tolkien rewrote the text in question. In LT2:344, yondo is said to mean "male descendant, usually (great) grandson", but in Tolkien's later Quenya, yondo means "son", and the word is so glossed in LT2:342. Dative yondon in VT43:36 (here the "son" in question is Jesus). See also yonya. At one point, Tolkien rejected the word yondo as "very unsuitable" (for the intended meaning?), but no obvious replacement appeared in his writings (PE17:43), unless the (ephemeral?) form anon (q.v.) is regarded as such. In one source, yondo is also defined as "boy" (PE17:190).
yonyo
son, big boy
yonyo noun "son, big boy". In one version, yonyo was also a term used in children's play for "middle finger" or "middle toe", but Tolkien may have dropped this notion, deciding to use hanno "brother" as the alternative play-name (VT47:10, 15, VT48:4)
A prefix appearing as an element in yomenië “meeting, gathering (of three or more coming from different directions)” in the Quendi and Eldar essay from 1959-60 (WJ/407). It is clearly based on primitive ✶jō(m) “together” as the plural equivalent of ✶wō (WJ/361), and thus likely means “together (of three or more things)”.
Conceptual Development: The Qenya Lexicon of the 1910s had ᴱQ. so- “together, grouped” under the early root ᴱ√SŌ, a prefixal equivalent of ᴱQ. le “with (accompaniment)” (QL/85). Given the gloss “grouped”, I think so- also applied to multiple items grouped together.