the world > matter > properties of materials > temperature > heat > burning > burn or be on fire [verb (intransitive)] > catch fire or begin to burn > of fire: to catch (3)
intransitive. Of fire: to catch, to take hold. Obsolete. rare.
intransitive. spec. Of fire: to begin to act on a substance; to take hold.
Of fire, flames, etc. intransitive. To take hold; to spread; to begin to burn more strongly. Also in figurative contexts.