Englishbatty
adjective
British, informal
she has gone completely batty:
mad, insane, odd, eccentric, deranged, demented, crazed, out of one's mind, not in one's right mind, sick in the head, lunatic, unbalanced, unhinged, unstable;
mad as a hatter, mad as a March hare, foaming at the mouth;
foolish, stupid, idiotic, silly;
informal crazy, mental, daft, bats, bonkers, nuts, nutty, nutty as a fruitcake, loony, screwy, off one's head/nut/rocker, round the bend, out to lunch, raving mad, stark raving mad;
British, informal barmy, crackers, barking (mad), stark staring mad, dotty, potty, off one's trolley, off the wall, not the full shilling, away with the fairies;
North American, informal nutsy, whacko.
▷antonyms sane, rational.
batty (1) Oxford Dictionary of English