The soldiers, swinging their arms and keeping time spontaneously, marched with long steps.
Its vapour is spontaneously inflammable when exposed to air.
His sermons especially abound in quotations and allusions, which have the air of spontaneously suggesting themselves, but which must sometimes have baffled his hearers.
Monoclinic sulphur, obtained by crystallizing fused sulphur, melts at I 19.5°, and admits of undercooling even to ordinary temperatures, but contact with a fragment of the rhombic modification spontaneously brings about the transformation.
These forms are developed spontaneously, without suggestion from outside.