1.  dotty(s = adj.all) around the bend, balmy, barmy, bats, batty, bonkers, buggy, cracked, crackers, daft, fruity, haywire, kookie, kooky, loco, loony, loopy, nuts, nutty, round the bend, wacky, whacky - informal or slang terms for mentally irregular; "it used to drive my husband balmy"

2.  dotty(s = adj.all) crazy, gaga, wild - intensely enthusiastic about or preoccupied with; "crazy about cars and racing"; "he is potty about her"

dotty, adj. (dottier, dottiest) colloq.
1 feeble-minded, silly.
2 eccentric.
3 absurd.
4 (foll. by about, on) infatuated with; obsessed by.

Derivative:
dottily adv. dottiness n.

Etymology:
earlier = unsteady: f. DOT(1) + -Y(1)