/herr'kyeuh lee"euhn, herr kyooh"lee euhn/ , adj.
1. requiring the great strength of a Hercules; very hard to perform: Digging the tunnel was a herculean task.
2. having enormous strength, courage, or size.
3. ( cap. ) of or pertaining to Hercules or his labors.
[ 1590-1600; Hercule ( us ) of, belonging to HERCULES + -AN ]
Syn. 1. prodigious, arduous, onerous, formidable.