Early Primitive Elvish
reðe
root. kinsman
rese
root. kinsman
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!
reðe
root. kinsman
rese
root. kinsman
The form reðe was a root added under ᴱ√RESE [REÞE] “aid, support” in the Qenya Lexicon of the 1910s, with derivatives of ᴱ√RESE having to do with “kinship” reassigned to reðe, such as ᴱQ. renda “related, of the same kin or clan” and ᴱQ. resse “kinswoman, cousin” (QL/79). In the contemporaneous Gnomish Lexicon Tolkien had a similar set of words likewise derived from distinct reth- vs. redh-, with the latter most likely being the basis for words like G. redhin “related” and G. ress “cousin (f.), relative” (GL/65). The root was given as RESE- “kinsman” in the Poetic and Mythological Words of Eldarissa (PME/79), but the addition of reðe may be later than that document.
Neo-Eldarin: For purposes of Neo-Eldarin, I think it is worth positing a Neo-Root ᴺ√RE(N)D to preserve these early kinship and cousin words, for which we have no later alternatives. It might be considered a variant of later root √RED “scatter, sow” (Ety/RED; PE19/91) and thus applied only to more distant kin.