Source : Webster's Revised Unabridged Dictionary (1913)

Self-evident \Self`-ev"i*dent\, a.
   Evident without proof or reasoning; producing certainty or
   conviction upon a bare presentation to the mind; as, a
   self-evident proposition or truth. -- {Self`-ev"i*dent*ly},
   adv.

Source : WordNet®

self-evident
     adj : evident without proof or argument; "an axiomatic truth"; "we
           hold these truths to be self-evident" [syn: {axiomatic},
            {taken for granted(p)}]