This is the verse translation, not a definition of the individual word.
Can they be like those who are upon clear proof from their Lord, backed by a witness [i.e., Gabriel] from Him, and before it was the Book of Moses a guide and mercy? Such people believe in it. But whoever of the factions[1] disbelieves in it, the Fire will be their promised end. So have no doubt about it, for it is the truth from your Lord, but most people do not believe.
Source
[1] i.e., Jews, Christians and all other non-Muslim nations.