The Collaborative International Dictionary of English v.0.48:

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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