The word ᴱQ. oswe “hip” appeared in the Qenya Lexicon of the 1910s under the early root ᴱ√OSO¹ whose other derivative was ᴱQ. oksa “joint” (QL/71).

Neo-Quenya: I’d retain the word ᴺQ. oswë “hip” for purposes of Neo-Quenya, but it cannot be derived from √OS any longer. I would assume it is derived from a √OTH, a variant of ᴹ√OS “round” (perhaps originally referring to the round joint), and hence archaically oþwe; compare [ᴹQ.] hiswa < ᴹ✶khithwa (Ety/KHIS).