Synonyms of unbidden

1 Syllable

free, down

2 Syllables

willing, simple, casual, offhand, ad-lib

3 Syllables

unasked, spontaneous, unstudied, unartful, free-willed, natural, impromptu, unplanned, unconscious, impetuous, unprompted, unforced, off-the-cuff

4 Syllables

improvised, uncompelled, uncontrived, unprescribed, undemanded, voluntary, automatic, extempore, instinctive, unconstrained, uncontrolled, unrequested

5 Syllables

unpremediated, extemporaneous, inevitable, unintentional, involuntary, irresistible, unavoidable

6 Syllables

unsophisticated