Green’s Dictionary of Slang

fuckwit n.

1. [1980s+] (orig. Aus.) a general term of derision.

2. (also F-wit) a fool; thus fuckwit, adj., stupid, foolish .

In derivatives

fuckwittage (n.)

[2005] stupidity, foolishness.

fuckwitted (adj.)

[1970s+] (Aus./N.Z.) stupid, foolish.

fuckwittery (n.)

[2000s+] stupidity, foolishness.

fuckwittism (n.)

[1970s] (Aus.) stupidity, foolishness.