Webster's Revised Unabridged Dictionary · 1913

Labellum

Labellum (lȧ*bel"lum) , noun

[Latin, dim. of labrum lip.]

1.
(Botany) The lower or apparently anterior petal of an orchidaceous flower, often of a very curious shape.
2.
(Zoology) A small appendage beneath the upper lip or labrum of certain insects.