Quenya 

pir-

spin, turn

pir- "spin, turn" (apparently intransitive). Actually cited in the form piri-, perhaps with the connecting vowel of the aorist included. "Qenya" pa.t. pírë. (QL:74)

Sindarin 

pir-

verb. to stir, stir round, make spin

Sindarin Group: Eldamo - neologism/adaptations. Published by

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!

Gnomish

cwir-

verb. to stir, stir round, make spin

A verb appearing as G. cwir- “to stir, stir round, make spin” in the Gnomish Lexicon of the 1910s (GL/29), clearly a cognate to ᴱQ. qiri- “stir (make spin)” in the contemporaneous Qenya Lexicon and thus derived from a variant of the early root ᴱ√QIŘI [QIÐI] (QL/77).

Neo-Sindarin: A similar root √KWER “revolve” appeared in Tolkien’s later writings (PE17/65), so I think a Neo-Root ᴺ√KWIR “stir, spin” might be used as a variant of that root. As such, I would update this Gnomish word to ᴺS. pir- “to stir, stir round, make spin”, since (unlike in Gnomish of the 1910s) [[at|[kw] became [p]]] in Sindarin of the 1950s and 60s.