MIDRIB
midrib, midvein
(noun) the vein in the center of a leaf
Source: WordNet® 3.1
Etymology
Noun
midrib (plural midribs)
(botany) The strengthened vein down the middle of a flower petal or simple leaf or leaflet.
Synonyms: middle rib, midvein
(botany) The continuation of the petiole of a pinnately compound leaf around which the leaflets attach.
Synonyms: middle rib, rachis
Synonyms
• midnerve
• midvein
Source: Wiktionary
Mid"rib`, n. (Bot.)
Definition: A continuation of the petiole, extending from the base to the
apex of the lamina of a leaf.
Source: Webster’s Unabridged Dictionary 1913 Edition