Synonyms for Goof:

n.

joker, maniac, dumb blond, numpty. ability, cretin, ding-dong, dip, error, flaw, fool, gander, imbecile, jerk, misapprehension, moron, nerd, nincompoop, ninny, nitwit, schmuck, simple, simpleton, tomfool, turkey, Mooncalf, schmo, mix up, softhead. bloomer, blooper, bull, correct, fall short, let down, miss, Foozle, trip-up, mess up, slip up, foul up. diddle, goldbrick, idle, industrious, laze, loaf, loiter, lounge, shirk. blunder (noun)
blooper, error, fluff.
boob (noun)
fathead.
bungler (noun)
blockhead, bonehead, botcher, bumbler, bungler, clod, clodhopper, clown, dolt, fumbler, oaf, yokel, blunder-head, butter-fingers.
dunce (noun)
blockhead, bonehead, dolt, fool, imbecile, jerk, moron, nincompoop, ninny, nitwit, oaf, simpleton.
error (noun)
flaw, misapprehension.
goof (noun)
blunder, boob, bozo, cuckoo, fathead, goose, sin, twat, zany.
schlemiel (noun)
schmuck.
screwball (noun)
bozo.

v.

blow (verb)
fail, miss.
err (verb)
blunder, botch, bungle, err, fluff, mar, miscalculate, misconceive, misconstrue, misestimate, misjudge, sin, slip, stumble, trip, slip up.
goof (verb)
blunder, botch, bungle, err, flub, miscalculate, slip, mess up, mix up, foul up.

Other synonyms:

bloomer, blooper, cretin, ding-dong, error, nerd, ninny, schmuck, tomfool, Foozle, schmo, softhead. imbecile, moron, nincompoop, nitwit, simpleton, turkey, Mooncalf. fool, gander, loiter, shirk. simple. blow
miss.
err
slip, slip up.
Other relevant words:
bloomer, blooper, boob, bozo, bull, cretin, cuckoo, diddle, ding-dong, dip, error, fail, fathead, flaw, flub, fool, gander, goldbrick, goose, idle, imbecile, jerk, laze, loaf, loiter, lounge, misapprehension, miss, moron, nerd, nincompoop, ninny, nitwit, schmuck, shirk, simple, simpleton, sin, tomfool, turkey, twat, zany, Mooncalf, Foozle, schmo, softhead, make a mistake.

Usage examples for goof

  1. Know what that goof ball Mex was doing, before? – The Planet Strappers by Raymond Zinke Gallun
  2. When the Martian Mangler gallops over to his corner, my bum has went through the ropes and quick runs around on the apron to the other side and comes at the Martian from behind before the goof knows what's happening. – Hoiman and the Solar Circuit by Gordon Dewey
  3. Or Gertie the goof – Gigolo by Edna Ferber