In PE17 we have rhaed "a peculiar hue, a kind of fashion" attested, Tolkien says it is particularly used of colours and shapes, but by extension can be applied to a broader term "kind, type" I think. In other cases noss can be used (with the meaning "species")

In light of Qenya nostalë, Latin genus and Welsh rhyw, using a Sindarin noun from (O)NO, (O)NOS does come to mind as one option — versus a semantically sensible neologism from, say, SAT 'appropriate, set aside, limit' (*satnâ/S *sann- or longer stem + an abstract element; or *sat-mâ > *sanu ?) and what Tamas suggested.

*goeifred containing IM (Q imya) = "consimilarity"?

I wonder what's the etymology of the Welsh synonym math (not given by Morris-Jones or Alan Ward).

Also worth noting here is Gnomish thlim "race, kind, species, sort" which would correspond to a Sindarin-stage form *?lhim(m-) [i/e]. Of course, its proper mature Sindarin counterparts may be lî, rim ("a people of one kind or origin", PE17:190) and nothlir (WJ:237); note also the 1960's plural element -lir (used for animates) and Noldorin lhîr "row, range".