arcminute

Angleexact by definition

The arcminute is exactly 1/60 of a degree, or 1/21,600 of a full turn. It is used in navigation, surveying and astronomy where whole degrees are too coarse. The definition is exact, though the radian value 2.9089 × 10⁻⁴ is irrational and rounded here.

1 0.016666667 °
Where the unit came from

The name comes from the Latin pars minuta prima, the "first small part" of a degree, the same phrase that gave the minute of time. On the Earth's surface, one arcminute of latitude is one nautical mile by construction.