A device that produces and radiates heat, typically to raise the temperature of a room or building.
"The old heater struggled to keep the freezing garage warm on such a cold night."
In plain English: A heater is an appliance that warms up air, water, or other things to make them hot and comfortable.
"I turned on the heater because the room was freezing cold."
Usage: A heater is any appliance designed specifically to warm up rooms or buildings by producing radiant heat. While often used interchangeably with "furnace," a heater generally refers to smaller units like space heaters rather than whole-house heating systems.
A surname.
"The local baseball team was captained by Heater, a popular family name in the town."
The word heater is formed by adding the suffix "-er" to the root word heat. This construction indicates a person or thing that performs the action of heating something up.