"to affix a label to," c. 1600, see label (n.); figurative sense of "to categorize" is from 1853. Related: Labeled; labeling; labelled; labelling.

in anatomy and zoology, "lips or lip-like parts," a Modern Latin use of Latin labia "lips," plural of labium "lip" (see lip (n.)). Specifically as "the folds on either side of the vulva" (labia pudendi) from 1630s; further classified as labia majora (the outer folds, 1813; the singular is labium majus) and labia minora (inner folds, 1781; the singular is labium minus). The lips of the mouth are labium superior (upper) and labium inferiore (lower).

"pertaining to the lips," 1590s, from Medieval Latin labialis "having to do with the lips," from Latin labium "lip" (see lip (n.)). The noun meaning "a labial sound" (one accomplished by complete closure of the lips) is from 1660s, from the adjective in this sense (1590s). Related: Labially.

1856, from labial + -ize. Related: Labialized; labializing.

"having a lip or lip-like part," 1706, from Modern Latin labiatus "lipped," from Latin labium "lip" (see lip (n.)).

mid-15c., "prone to lapse," from Latin labilis, from labi "to slip" (see lapse (n.)). Hence, in chemistry, "prone to undergo displacement" (c. 1600).

word-forming element in medical use since 17c., taken as a combining form of Latin labium "lip" (see lip (n.)).

"lip or lip-like part," 1590s, plural labia (q.v.), from Latin labium "lip" (see lip (n.)).

"belly," 1943, American English slang, probably from dialectal pronunciation of Italian la pancia "the belly," with the definite article absorbed, from Latin pantex (genitive panticis) "belly" (see paunch).

mid-14c., "manual worker," especially an unskilled one, agent noun from labor (v.). Meaning "member of the working class, member of the lowest social rank" is from c. 1400 (compare labour).