Noun, pl. labra
1. A flap-like structure that lies immediately in front of the mouth in almost all extant euarthropods, the general exception being provided by the probable chelicerate-relatives the pycnogonids. In entomology, the labrum is the upper lip of an insect mouth, the lower lip being termed the labium. (wikipedia.org)
2. The uppermost of the mouthparts (trophi) of a typical insect, such as a cockroach. Typically resembles an upper lip and forms part of the roof of the mouth in such insects. (wiktionary.org)
1. Any of several lip-like projections. (wiktionary.org)
2. Also refers to labium.
3. A fibrocartilaginous lip around the margin of the concave portion of some joints. (medilexicon.com)
Word origin: From Latin labrum, cognate with labium “lip”