Andy

masc. proper name, from Old French Andreu (Modern French André), from Late Latin Andreas (source also of Spanish Andrés, Italian Andrea, German Andreas, Swedish and Danish Anders), from Greek Andreas, a personal name equivalent to andreios (adj.) "manly, masculine, of or for a man; strong; stubborn," from anēr (genitive andros) "man" (from PIE root *ner- (2) "man").

Nearly equivalent to Charles. Andrew Millar (1590s) for some forgotten reason became English naval slang for "government authority," and especially "the Royal Navy." St. Andrew (feast day Nov. 30) has long been regarded as patron saint of Scotland; the Andrew's cross (c. 1400) supposedly resembles the one on which he was crucified.