Definition of water parsley in US English:

water parsley

noun

  • Any of various umbelliferous plants of damp or wet habitats, as (in early use) water parsnip (Sium latifolium) and wild celery (Apium graveolens), and (in later use) Oenanthe sarmentosa of western North America.

Origin

Mid 16th century; earliest use found in William Turner (d. 1568), naturalist and religious controversialist. From water + parsley.

Pronunciation

water parsley

/ˈwɔːtə ˌpɑːsli/