What is "mother's mark"

Mother \Moth"er\ (m[u^][th]"[~e]r), n. [OE. moder, AS. m[=o]dor; akin to D. moeder, OS. m[=o]dar, G. mutter, OHG. muotar, Icel. m[=o][eth]ir, Dan. & Sw. moder, OSlav. mati, Russ. mate, Ir. & Gael. mathair, L. mater, Gr. mh`thr, Skr. m[=a]t[.r]; cf. Skr. m[=a] to measure. [root]268. Cf. Material, Matrix, Metropolis, Father.]

1. A female parent; especially, one of the human race; a woman who has borne a child.

2. That which has produced or nurtured anything; source of birth or origin; generatrix.

   Alas! poor country! . . . it can not Be called our mother, but our grave.
   --Shak.

   I behold . . . the solitary majesty of Crete, mother of a religion, it is said, that lived two thousand years.
   --Landor.

3. An old woman or matron. [Familiar]

4. The female superior or head of a religious house, as an abbess, etc.

5. Hysterical passion; hysteria. [Obs.]
   --Shak.

   Mother Carey's chicken (Zo["o]l.), any one of several species of small petrels, as the stormy petrel ( Procellaria pelagica), and Leach's petrel ( Oceanodroma leucorhoa), both of the Atlantic, and Oceanodroma furcata of the North Pacific.

   Mother Carey's goose (Zo["o]l.), the giant fulmar of the Pacific. See Fulmar.

   Mother's mark (Med.), a congenital mark upon the body; a birthmark; a n[ae]vus.

n. A congenital mark upon the body; a naevus.