headroom
nounEtymology From head + room.
1
The vertical clearance above someone's head, as in a tunnel, doorway etc; room (space) for one's head.
2
The vertical measurement, top to bottom, for example for clearance under a bridge.
- With a rare and beautiful ease one can now ring up a boffin, as I did the other day, and say: "As a price for not opposing our Parliamentary Powers for a new marshalling yard, the Council at X demands that the bridge over X Lane shall have 16 ft. 6 in. headroom. This means steepening our gradient from 1 in 70 to 1 in 65 for half a mile on a 20-chain curve. What difference will this make to the loads of Type "2", "3" and "4" diesels please?". Back comes the answer.1960 April, G. F. Fiennes, “Unpunctuality - the cause and the cure”, in Trains Illustrated, page 244:
- The new bridge (6) gives headroom of 13ft at high tide, sufficient for present-day river traffic.1963 April, “Chepstow Bridge is rebuilt”, in Modern Railways, page 265, photo caption:
3
Business, Electrical engineering, Electricity, Electromagnetism, Electronics, Energy, Engineering, Natural sciences, Physical sciences, Physics The ability of a system to reproduce loud sounds free of distortion; dynamic headroom.
- […] the difference between signal-to-noise ratio and overload reserve (headroom) as well as noise (safety) margin (footroom).2000, Wolfgang Ahnert, Frank Steffen, Sound Reinforcement Engineering: Fundamentals and Practice, page 177:
4
The distance between the actual performance of an algorithm and its maximum possible performance.
5
Synonym of headspace (“space between the top of the contents of a container and its seal”).
- For whole pickles and fruit preserves, leave no less than ½ inch of headroom at the top of the jars […]2014, Damon Lee Fowler, Beans, Greens, & Sweet Georgia Peaches: The Southern Way of Cooking Fruits and Vegetables, 2nd edition, Guilford: Globe Pequot Press, →ISBN, page 11: