phugoid

Meanings

1. Of the motion of an aircraft, missile, or other flying object: continuously oscillating in a vertical plane due to the object pitching up and climbing, thus slowing down; then pitching down and descending, thus speeding up.

1. The motion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane due to the object pitching up and climbing, thus slowing down; then pitching down and descending, thus speeding up.

Etymology

The adjective is a learned borrowing from Ancient Greek φῠγή (phŭgḗ, “fleeing, flight; escape; retreat”) (ultimately from Proto-Indo-European *bʰewg- (“to flee”)) + English -oid (“suffix meaning ‘having the likeness of, resembling’, forming adjectives and nouns”). The word was coined by the British aerodynamicist and engineer Frederick W. Lanchester (1868–1946) in his book Aerodonetics (1908), the author mistaking the meaning of φῠγή (phŭgḗ) to be “flight” in the sense of “the act of flying”: see the quotations. The noun is derived from the adjective.