daft

Mane (Îngilîzî)

1. (Australia, British, Ireland, New-Zealand, informal) Foolish, silly, stupid.
2. (Australia, British, Ireland, New-Zealand, informal) Crazy, insane, mad.
3. (obsolete) Gentle, meek, mild.

Têgeh

dîn

Hevwate

silly

foolish

crazy

mad

nutty

barmy

loony

bats

haywire

insane

around the bend

nuts

balmy

deranged

batty

buggy

daffy

cracked

whacky

wacky

kookie

doltish

round the bend

dotty

crackers

weak-headed

loopy

loco

kooky

bonkers

light-headed

stupid

fruity

fool

flighty

feebleminded

fatuous

crackpot

dull-witted

dull

insensate

dopey

blithering

inept

incipient

inane

imbecilic

distraught

imbecile

idiotic

Werger

tonto

doof

verrückt

idiot

dingue

cinglé

fou

branque

ανόητος

παλαβός

deli

dément

barjo

bête

blöd

Wekî (IPA) tê bilêvkirin

/dɑːft/

Etîmolojî (Îngilîzî)

Ji Middle English mîras hatiye girtin: dafte

Ji Old English mîras hatiye girtin: dæfte

Hevwate bi Old English: dafnian

Hevwate bi rûsî: до́брый

In summary

From Middle English dafte, defte (“gentle; having good manners; humble, modest; awkward; dull; boorish”), from Old English dæfte (“accommodating; gentle, meek, mild”), from Proto-West Germanic *daftī (“fitting, suitable”), ultimately from Proto-Indo-European *dʰh₂ebʰ- (“fitting; to fit together”). Related to Old English dafnian, dafenian (“to be fitting, appropriate, or becoming”), Russian до́брый (dóbryj, “good”).
Compare silly which originally meant “blessed; good, innocent; pitiful; weak”, but now means “laughable or amusing through foolishness or a foolish appearance; mentally simple, foolish”.
Unrelated to, though perhaps influenced by, daff (“fool (n.); to be foolish (v.)”) (past form daffed).