masc. proper name, from Latin, from Greek Alexandros "defending men," from alexein "to ward off, keep off, turn (something) away, defend, protect" + anēr (genitive andros) "man" (from PIE root *ner- (2) "man"). The first element perhaps is related to Greek alke "protection, help, strength, power, courage," alkimos "strong;" and cognate with Sanskrit raksati "protects," Old English ealgian "to defend."

As a kind of cocktail recipe featuring crème de cacao and cream, Alexander is attested from 1913; the reason for the name is unclear.

Latin, "(with) God (as our) defender," national motto of the Confederate States of America, from ablative of Deus "God" (see Zeus) + ablative of present participle of  vindicare "to liberate; to act as avenger; protect, defend" (see vindication).

"to fight for, defend, protect, maintain or support by contest," 1820 (Scott) in a literal sense, from champion (n.). Figurative use, "maintain the cause of, advocate for" is by 1830. Earlier it meant "to challenge" (c. 1600). Related: Championed; championing.

c. 1400, "keep from view or use," from shut (v.) + up (adv.). Meaning "cause to stop talking" is from 1814; intransitive meaning "cease from speaking" is from 1840. Put up or shut up "defend yourself or be silent" is U.S. slang, by 1868.

"to take heed of, beware," Old English warian "to guard against, beware; protect, defend," from Proto-Germanic *warō (source also of Old Frisian waria, Old Norse vara), from PIE *waro- "to guard, watch," suffixed form of root *wer- (3) "perceive, watch out for."

1570s, of medicines, "that tends to prevent or defend from disease," from French prophylactique (16c.) and directly as a Latinized borrowing of Greek prophylaktikos "precautionary," from prophylassein "keep guard before, ward off, be on one's guard," from pro "before" (see pro-) + phylassein, Ionic variant of phylattein "to watch over, to guard," but also "cherish, keep, remain in, preserve," from phylax "guard," a word of unknown origin.

The noun is first recorded 1640s, "a medicine or treatment to prevent or defend against disease;" meaning "condom" is from 1943, replacing earlier preventive (1822), preventative (1901). Condoms originally were used more to thwart contagious disease than to prevent pregnancy. Related: Prophylactical.