Rheum (family Polygonaceae) A genus of herbs in which the leaves are large and palmately lobed. The inflorescence is an erect panicle; the flowers are small and entomophilous. Rhubarb is the petiole of R. rhaponticum, and medicinal rhubarb (a purge) is R. officinale. There are about 50 species, occurring in temperate and subtropical Asia.

rheum watery matter secreted by mucous glands or membranes; mucous discharge, catarrh XIV; (poet.) tears XVI. ME. reume — OF. reume (mod. rhume) — late L. rheuma — Gr. rheûma flow, stream, bodily humour.
So rheumatic consisting of watery discharge XIV; suffering from, characterized by this XVI. — OF. reumatique (mod. rhu-) — L. — Gr. rheumatism; rheumatic disease XVII. — F. or L. — Gr. rheumatoid XIX.

rheum / roōm/ • n. chiefly poetic/lit. a watery fluid that collects in or drips from the nose or eyes.