One of the mysteries of the English language finally explained.
Synonyms of duffer in English:
duffer
See definition of duffer
noun
1‘he's such a duffer—we shouldn't have hired him’
bungler, blunderer, incompetent, oaf, dunce, dolt, dunderhead, fool, idiot, booby, stupid person, moron, cretin, imbecile
chump, clot, clod, nitwit, dimwit, airhead, birdbrain, lamebrain, pea-brain, numbskull, thickhead, fathead, blockhead, bonehead, meathead, chucklehead, knucklehead, pinhead, wooden-head, dipstick, dumb-bell, dumbhead, dumbo, dum-dum, noodle, donkey, ass, nerd
British berk, divvy, wally, numpty, wazzock, nit, mug, prat, twerp, twonk, pillock, muppet
Scottish balloon, galoot, cuddy, nyaff
North American doofus, goofball, goof, putz, bozo, boob, lamer, chowderhead, meatball, lummox, dummy, turkey, clunk, ding-a-ling, palooka
NZ Australian galah, drongo, alec, dingbat
British vulgar slang knobhead
North American vulgar slang asshat