unbidden

Unbid \Un*bid"\ ([u^]n*b[i^]d"), Unbidden \Un*bid"den\, a.
   1. Not bidden; not commanded.
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            Thorns also and thistles it shall bring thee forth
            Unbid; and thou shalt eat the herb of the field.
                                                  --Milton.
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   2. Uninvited; as, unbidden guests. --Shak.
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   3. Being without a prayer. [Obs.] --Spenser.
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43 Moby Thesaurus words for "unbidden":
      arbitrary, autonomous, discretional, discretionary, elective, free,
      free will, gratuitous, independent, nonmandatory, offered,
      optional, proffered, self-acting, self-active, self-determined,
      self-determining, spontaneous, unacceptable, unagreeable, unasked,
      unasked-for, unbesought, uncalled-for, uncoerced, uncompelled,
      undesirable, undesired, unforced, uninfluenced, uninvited,
      unpressured, unprompted, unrequested, unrequired, unsolicited,
      unsought, unwanted, unwelcome, unwished, voluntary, volunteer,
      willful