Etymology 1
See dote, or compare totty (“unsteady, dizzy”).
Adjective
dotty (comparative dottier, superlative dottiest)
- (British, colloquial) Mildly insane or eccentric; often, senile.
My nan has got dottier and dottier since passing the age of eighty.
1897, Richard Marsh, The Beetle:Knockers in this part of the world seem intended for ornament only, — nobody seems to pay any attention to them when they’re used. The old lady upstairs must be either deaf or dotty.
1970, Roald Dahl, Fantastic Mr. Fox, New York: Alfred A. Knopf, page 45:Mr. Fox stopped digging and stared at Badger as though he had gone completely dotty. "My dear old furry frump," he said, "do you know anyone in the whole world who wouldn't swipe a few chickens if their children were starving to death?"
- (UK, dated) Having an unsteady gait.
Etymology 2
From dot + -y.
Noun
dotty (plural dotties)
- (MLE) A shotgun.
2013, “Mad Years”, in Potter Payper (lyrics), Training Day, performed by Potter Payper:Never bummy but I'm scummy fam, I used to burgle houses
Then some OGs was consignin me them ounces
Wet man round me had me feeling like I’m drownin
Fam we really went there with a brownin
Me and next man really went there with a dotty
05 murder squad nicked me for a [censored]
2017, “Mad About Bars”, TMula (lyrics), performed by 86 (TMula x Scrams):They dont know what I’ve been through
Red dot on his head like a hindu
Scrams, Face just stack for the Wesson
Ca’ be the gunplay that we’re into
It’s like them man chill with the singer
Two dot dots there in the dinger
Yard man’s got a dotty in the rave
But he’s still tryna do the La Linga
We’ve had guns and shanks without awareness
We’ve had guns and shanks we’re so fearless
2017, “Next Up?”, Digga D (lyrics), performed by 1011 (Digga D x Sav'O x T.Y):Bro I’m booky, I’ll take your food if my belly starts rumblin
They rap about bootings, they ain’t blammed nobody
Hold that properly when I bang that dotty
I put sniff in a rex, and I slang that bobby
2020, “Respawn”, Cillian (lyrics), chorus:I’m out here from the night till dawn
The dotty’s out but I like it sawn