Source : Webster's Revised Unabridged Dictionary (1913)

Unbid \Un*bid"\, Unbidden \Un*bid"den\, a.
   1. Not bidden; not commanded.

            Thorns also and thistles it shall bring thee forth
            Unbid; and thou shalt eat the herb of the field.
                                                  --Milton.

   2. Uninvited; as, unbidden guests. --Shak.

   3. Being without a prayer. [Obs.] --Spenser.

Source : WordNet®

unbid
     adj : not invited or requested; "unbidden guests"; "comments unbid
           and unwelcome" [syn: {unasked}, {unbidden}]