Dim Witted means your stupid and portly is a nice way to say you're fat.
the man in the play was so dim-witted for that part
Phoebe
Phoebe
That they were dim witted.
Thick
Opposites could be unclever, unskilled, or dim-witted.
boring, dim, dumb, wearisome, dense, backward, tedious, dim-witted.
dense, dim-witted, dull, foolish, moronic, simple minded
birdbrained, defective, dim,dim-witted, dopey, dull, imbecile.--- There are other words too but they seem offensive.
The opposites of cunning (clever) could be dim, dense, dull-witted, or unimaginative.
Dunno, it's just a saying lolActually, it refers to being absent-minded. It's derived from the twin characters Twiddle Dee and Twiddle Dum, who were dumb, in the classic Alice in Wonderland by Lewis Carroll.
Blockheaded or thickheaded Dense Dumb Dim-witted Hebetudinous Idiotic