I’ll echo others on Wiktionary: it has astounding range.
For ancient Greek, don’t bother with Liddell-Scott: its etymologies are antiquated. Check both Chantraine and Frisk. Both are under copyright, and I can neither confirm nor deny that both are available at a reputable academic archiv al org anisation.
We are served quite well for later stages of Greek. For contemporary Greek, I go to the Triantafyllidis dictionary by default, because it is online.