n.
Pronunciation: p ī - ' r ē -thr ə n, - ' re-
Function: noun
Etymology: International Scientific Vocabulary, from Latin pyrethrum
Date: 1871
: either of two oily liquid esters C 21 H 28 O 3 and C 22 H 28 O 5 having insecticidal properties and occurring especially in the flowers of pyrethrum