unprompted[adjective]Synonyms: spontaneous, automatic, impulsive, instinctive, involuntary, unmeditated, unpremeditated, will-less
[TahlilGaran] English Synonym Dictionary ▲
un‧prompt‧ed /ʌnˈprɒmptəd, ʌnˈprɒmptɪd $ ʌnˈprɑːmp-/
adjective formal said or done without anyone asking you to:
Quite unprompted, he offered to help. [TahlilGaran] Dictionary of Contemporary English ▲