Meanings
- not comparableaeronauticsOf 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.
The Phugoid theory deals with the longitudinal stability, and the form and equations of the flight path of an aerodone.
1908, F[rederick] W[illiam] Lanchester, “The Phugoid Theory—The Equations of the Flight Path”, in Aerodonetics: Constituting the Second Volume of a Complete Work on Aerial Flight […], London: Archibald Constable & Co. […], →OCLC, § 18 (Introductory), page 37
plural phugoids · alternative fugoid
- aeronauticsThe 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.
As well as physical debris, the report drew on recent analysis by Australian defense scientists of burst frequency signals from Flight 370 to satellites that indicated the aircraft had been descending fast, likely in an automated series of swooping dives called fugoids.
2016 November 2, Rob Taylor, “Malaysia Airlines Flight 370 likely in steep dive before crash”, in The Wall Street Journal, New York, N.Y.: Dow Jones & Company, →ISSN, →OCLC, archived from the original on 26 Mar 20231 more example
As the amplitude of the phugoid is increased beyond the limits of the semicircle, there is a rapid shortening of the time period as shown by the manner in which the time curve falls away almost immediately after that critical form of flight path is passed. […] [I]f we select phugoids of greater and greater velocity, for a given aerodone the form of the tumbler curve approximates more and more closely to a circle of radius #61;2H#95;n.
1908, F[rederick] W[illiam] Lanchester, “The Phugoid Theory—The Flight Path Plotted”, in Aerodonetics: Constituting the Second Volume of a Complete Work on Aerial Flight […], London: Archibald Constable & Co. […], →OCLC, § 35 (The Time Period and Form of the Phugoid Path. Special Cases (continued).), page 63
Origin
- Proto-Indo-European*bʰewg-“to flee”
- Ancient Greekφῠγή“fleeing, flight; escape; retreat”
- Englishphugoid
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.
More words from Ancient Greek, Proto-Indo-European
Full word history & related roots →Translations
Arabic فوغويد
- فوغويد (fūgūyd)motion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
Chinese Mandarin 起伏運動 /起伏运动, 週期運動 /周期运动
- 起伏運動 /起伏运动 (qǐfúyùndòng)motion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
- 週期運動 /周期运动 (zhōuqīyùndòng, zhōuqíyùndòng)motion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
Finnish fugoidi-, korkeus-nopeusheilahtelun omainen
- fugoidi-of the motion of an aircraft, missile, or other flying object: continuously oscillating in a vertical plane
- korkeus-nopeusheilahtelun omainenof the motion of an aircraft, missile, or other flying object: continuously oscillating in a vertical plane
- fugoidimotion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
- fugoidiliikemotion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
- korkeus-nopeusheilahtelumotion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
French phugoïde
- phugoïdemotion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
German Phygoide
- Phygoidemotion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
Italian fugoide
- fugoidemotion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
Japanese フゴイド運動
- フゴイド運動 (fugoidoundō)motion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
Korean 푸고이드
- 푸고이드 (pugoideu)motion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
Romanian fugoidă
- fugoidămotion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
Russian фуго́ид
- фуго́ид (fugóid)motion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
Spanish fugoide
- fugoidemotion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
Swedish phugoidrörelse, fugoidrörelse
- phugoidrörelsemotion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
- fugoidrörelsemotion of an aircraft, missile, or other flying object continuously oscillating in a vertical plane
Cite this entry
phugoid. (n.d.). In WatkinsX Dictionary. Retrieved November 2, 2026, from https://dictionary.watkinsx.com/word/phugoid
“phugoid.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/phugoid. Accessed November 2, 2026.
WatkinsX Dictionary, s.v. “phugoid,” accessed November 2, 2026, https://dictionary.watkinsx.com/word/phugoid.
Source: phugoid on Wiktionary, CC BY-SA 4.0.