/spɑːnˈteɪniəs/
spon·tan·eous
BrE /spɒnˈteɪniəs/
NAmE /spɑːnˈteɪniəs/
not planned but done because you suddenly want to do it
a spontaneous offer of help
The audience burst into spontaneous applause.
often doing things without planning to, because you suddenly want to do them
(specialist)
happening naturally, without being made to happen
▸
spon·tan·eous·ly
BrE /spɒnˈteɪniəsli/
NAmE /spɑːnˈteɪniəsli/
We spontaneously started to dance.
The bleeding often stops spontaneously.