bravo (interj.)

"well done!," 1761, from Italian bravo, literally "brave" (see brave (adj.)). Earlier it was used as a noun meaning "desperado, hired killer" (1590s). Superlative form is bravissimo.

It is held by some philologists that as "Bravo!" is an exclamation its form should not change, but remain bravo under all circumstances. Nevertheless "bravo" is usually applied to a male, "brava" to a female artist, and "bravi" to two or more. ["Elson's Music Dictionary," 1905]

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Definitions of bravo from WordNet
bravo (n.)
a murderer (especially one who kills a prominent political figure) who kills by a surprise attack and often is hired to do the deed;
Synonyms: assassin / assassinator
bravo (n.)
a cry of approval as from an audience at the end of great performance;
bravo (v.)
applaud with shouts of `bravo' or `brava';