ᴹ√RIM root. “abound; large number”
A root in The Etymologies of the 1930s glossed “abound” with derivatives such as ᴹQ. rimbe/N. rhim “crowd, host” (Ety/RIM). A likely precursor to this root appeared in the Qenya Lexicon of the 1910s as ᴱ√‘(A)ṚM(A)R and ᴱ√‘ṚMṚ with a Gnomish form ᴱ√grimri· (QL/32), indicating the actual primitive form was *ᴱ√ƷṚMṚ. Derivatives of this early root include ᴱQ. arm- “gather, collect” and G. grim “host, folk”, the last of these the likely precursor to N. rhim.
The root ᴹ√RIM also appeared in Primitive Quendian Structure: Final Consonants from 1937, glossed “host, large number” >> “number, plenty” (PE21/57). Quenya and Sindarin forms Q. rimbë and S. rim continued to appear in Tolkien’s later writing (Let/382; PE17/50; UT/318), so it is likely the root √RIM remained valid, especially given the prevalence of suffix -rim in Sindarin collective names.
References ✧ Ety/ÓROT, RIM; EtyAC/ORO, RIM; PE21/57