"mother," a word used especially by children and infants, 1570s, representing the native form of the reduplication of *ma- that is nearly universal among the Indo-European languages (Greek mamme "mother, grandmother," Latin mamma, Persian mama, Russian and Lithuanian mama "mother," German Muhme "mother's sister," French maman, Welsh mam "mother").

Probably a natural sound in baby-talk, perhaps imitative of sound made while sucking. Its late appearance in English is curious, but Middle English had mome (mid-13c.) "an aunt; an old woman," also an affectionate term of address for an older woman.

In educated usage, the stress is always on the last syllable. In terms of the recorded appearance of the variant or related words in English, mama is from 1707, mum is from 1823, mummy in this sense from 1839, mommy 1844, momma 1810, and mom 1867. Mamma's boy "soft, effeminate male" is by 1901. 

child's word for "mother," 1520s, diminutive of mam (see mamma). Meaning "black woman having the care of white children" (who often continued to call her mammy after they were grown) is by 1837, Southern U.S. dialect, a variant of mamma.

childish or colloquial shortening of mamma, by 1823. "Also applied colloq. to a middle-aged or elderly woman, esp. one in authority" [OED].

"of or pertaining to a breast," 1680s, from French mammaire (18c.) or Medieval Latin mammarius, from Latin mamma "breast" (see mamma).

word-forming element meaning "breast," from Latin mamma "breast" (which is cognate with mamma). The form mammato-, used in cloud terminology in reference to smooth, rounded shapes, is from Latin mammatus.

1844, U.S. variant of mamma. Variant spelling mommie attested by 1882. Mommy track "career path for women that puts priority on parenting" is attested by 1987. Related: Mommies; also see momma.

"mother," 1867, American English, perhaps a shortening of mommy; also see mamma. Adjectival phrase mom and pop to indicate a small shop or other business run by a married couple is by 1946.

"the class of Vertebrata containing all those animals which suckle their young and no other animals," 1773, from Modern Latin (Linnaeus, 1758), from neuter plural of Late Latin mammalis "of the breast," from mamma "breast," from PIE *mama and cognate with mamma. Also see -a (2)).

pet word for "mother," 1823, short for mummy (see mamma). In British sociology, used from 1957 in reference to "the working class mother as an influence in the lives of her children." Also sometimes a vulgar corruption of madam or ma'am.

1707, spelling variant of mamma. Meaning "sexually attractive woman" is attested by 1925 in African-American vernacular. Mamasan "woman in a position of authority," especially "woman in charge of a geisha-house" is by 1949, with Japanese san, an honorific title. Mama mia! as an exclamation of surprise, etc. is by 1848, from Italian, literally "mother mine!"