Source : Webster's Revised Unabridged Dictionary (1913)

Truthful \Truth"ful\, a.
   Full of truth; veracious; reliable. -- {Truth"ful*ly}, adv.
   -- {Truth"ful*ness}, n.

Source : WordNet®

truthful
     adj 1: expressing or given to expressing the truth; "a true
            statement"; "gave truthful testimony"; "a truthful
            person" [syn: {true}] [ant: {untruthful}]
     2: conforming to truth; "I wouldn't have told you this if it
        weren't so"; "a truthful statement" [syn: {so(p)}]