Verse meaning
This is the verse translation, not a definition of the individual word.
May Allah pardon you [O Prophet]! Why did you give them permission [to stay behind] before it became clear to you as to who were telling the truth, and who were liars[1]?
Source
[1] None should have been given permission, so as to see who would set out with the Muslim army, the truthful; and who would not, the liars.
Source: QuranEnc.com · English Translation - Rowwad Translation Center
Listen to the verse context