fem. proper name, from Latin Marcia, fem. of Marcius, a Roman gens name, related to Marcus (q.v.).
masc. proper name, variant of Marcus (q.v.). Among the top 10 names given to boy babies born in the U.S. between 1955 and 1970.
Mark Twain is the pseudonym of American writer and humorist Samuel Langhorne Clemens (1835-1910), who had been a riverboat pilot; he took his pen name from the cry mark twain, the call indicating a depth of two fathoms, from mark (n.1) in a specialized sense of "measured notification (a piece of knotted cloth, etc.) on a lead-line indicating fathoms of depth" (1769) + twain.
"member of the Rastafarian sect," 1955 (Rastafarite is found from 1953), from Rastafari, Jamaican religion built around writings of Marcus Garvey and the belief that Haile Selassie (1892-1975), emperor of Ethiopia, was God. From Ras Tafari, Selassie's title from 1916 to his accession in 1936, from Amharic ras "chief, head" (from Arabic ra's) + tafari "to be feared." As an adjective from 1960.
Roman surname of the Junian gens. Its association with betrayal traces to Marcus Junius Brutus (c. 85 B.C.E.-42 B.C.E.), Roman statesman and general and conspirator against Caesar. The Brutus (Englished as Brute) who was the mythological eponymous founder of Britain in medieval legend was said to be a descendant of Aeneas the Trojan.