typhoid mary noun Usage: usually capitalized T&M Etymology: after Typhoid Mary, name given to Mary Mallon died 1938 Irish cook in United States who was found to be a typhoid carrier : one that is by force of circumstances a center or focus from which something undesirable spreads < authoritarianism … is carried by Typhoid Marys, unwitting sources of infection — S.P.Hayes b. 1910 >