1.
Spontaneous acts are not planned or arranged, but are done because someone suddenly wants to do them.
Diana’s house was crowded with happy people whose ~ outbursts of song were accompanied by lively music...
ADJ
~ly
As soon as the tremor passed, many people ~ly arose and cheered...
ADV: usu ADV with v, also ADV adj
2.
A ~ event happens because of processes within something rather than being caused by things outside it.
I had another ~ miscarriage at around the 16th to 18th week.
ADJ
~ly
Usually a woman’s breasts produce milk ~ly after the birth...
ADV: ADV after v