Headroom is the vertical space between your head and whatever is above you. In a car, headroom is the distance from the top of the seat to the roof. Tall basketball players sometimes complain about limited headroom in compact cars because their heads nearly touch the ceiling.

Buildings have headroom too. A basement with low headroom might force adults to duck when walking through doorways. Architects design staircases with enough headroom so people don't bump their heads on the ceiling above. Ships have notoriously tight headroom below deck, where even average-height sailors sometimes need to stoop.

The word also appears in technical contexts. In audio recording, headroom means extra capacity built into a system so it can handle sudden loud sounds without distortion. A recording engineer leaves headroom so an unexpected shout or drum crash doesn't ruin the recording.

Similarly, people talk about having headroom in a budget: extra money available for unexpected expenses. A family might keep some financial headroom for emergencies rather than spending every dollar they earn. In both cases, headroom means that comfortable extra space that keeps you from hitting a limit.