Definition of pern in English:

pern

Pronunciation /pəːn/

verb

(also perne)
  • In the poetry of W. B. Yeats, or with allusion to it: to spin, revolve; to move with a winding or spiral motion.

Origin

1920s; earliest use found in W. B. Yeats (1865–1939), poet. From pern, variant of pirn; adopted by W. B. Yeats from Irish dialect use.