Green’s Dictionary of Slang

(US) stupid, foolish, ineffectual; usu. describing a man; thus dweebette, the female equivalent.

1989		C. Hiaasen Skin Tight 137: Why’d you want to interview some dweeb P.I.?
1989		D. Waters Heathers [film script] I mean, do you really think if Betty Finns fairy godmother made her cool, she’d still hang out with her dweebette friends?
2002		‘Bootscooter’ August Moone 9:28 🌐 [H]er pesky dweeb twelve year old brother.