A large convex lens or concave mirror that can concentrate the sun's rays onto a small area, heating up the area and thus resulting in ignition of the exposed surface.

To kill (someone) by tying them to a post and setting a fire beneath them

(idiomatic) To neglect helping when one’s time is needed most; to ignore the major problem at hand (whilst doing something less important); to be idle, inactive, or uninterested in a time of great need.

Third-person singular simple present indicative form of burn the candle at both ends

Third-person singular simple present indicative form of fiddle while Rome burns

present participle of fiddle while Rome burns

Third-person singular simple present indicative form of burn that bridge when one comes to it

(idiomatic) To work studiously, especially late into the night.

(idiomatic) to harm oneself; to suffer consequences of one's actions.

A mild burn that causes redness of the skin but no blistering.