Source : Webster's Revised Unabridged Dictionary (1913)

Unassuming \Un`as*sum"ing\, a.
   Not assuming; not bold or forward; not arrogant or presuming;
   humble; modest; retiring; as, an unassuming youth; unassuming
   manners.

Source : WordNet®

unassuming
     adj : not arrogant or presuming; "unassuming to a fault, skeptical
           about the value of his work"; "a shy retiring girl"
           [syn: {retiring}]