departure

Here the word turns figurative. What is left behind is a norm rather than a place. It almost always takes from plus the thing abandoned, such as a plan, a practice or a standard. Prescott's History of the Reign of Philip the Second has "any departure from a national standard." Adjectives measure the distance: a slight, significant or bold departure. Because it is countable, one reform can contain several departures from current practice.

A gentle way of naming death, and an old one: Old French deporteure already meant both leaving and, figuratively, dying. The King James Bible of 1611 gives the solemn form, "The time of my departure is at hand," and Philip Sidney writes of a "timely departure." It suits elegy, sermon and condolence. In everyday speech it can be heard as ordinary leaving, so the context must make the death plain.

A navigator's distance, not an angle: the miles a ship has made east or west, worked out as distance sailed times the sine of the course angle. Plane sailing treats the track as if drawn on a flat chart, which is what lets simple trigonometry apply. Paired with difference of latitude, it gives the course made good. The surveyor's departure is the same idea applied on land.

Surveyors borrowed the east–west reckoning of the navigator's departure and applied it to lines on the ground. Each leg of a traverse has a departure (its difference in easting) and a latitude (its north–south component). The two travel together, usually in the plural: areas are "computed by latitudes and departures." Around a closed loop, the departures should sum to zero.

A fault in common-law pleading, not just a change of mind. A party who abandons the ground of an earlier pleading and sets up new matter breaks the continuity that successive pleadings require. Lawyers say a reply is "a departure" from the complaint, and a pleading that commits one can be struck as improper.