AskDefine | Define inclination

Dictionary Definition



1 an attitude of mind especially one that favors one alternative over others; "he had an inclination to give up too easily"; "a tendency to be too strict" [syn: disposition, tendency]
2 (astronomy) the angle between the plane of the orbit and the plane of the ecliptic stated in degrees [syn: inclination of an orbit]
3 (geometry) the angle formed by the x-axis and a given line (measured counterclockwise from the positive half of the x-axis) [syn: angle of inclination]
4 (physics) the angle that a magnetic needle makes with the plane of the horizon [syn: dip, angle of dip, magnetic dip, magnetic inclination]
5 that toward which you are inclined to feel a liking; "her inclination is for classical music" [ant: disinclination]
6 the property possessed by a line or surface that departs from the vertical; "the tower had a pronounced tilt"; "the ship developed a list to starboard"; "he walked with a heavy inclination to the right" [syn: tilt, list, lean, leaning]
7 a characteristic likelihood of or natural disposition toward a certain condition or character or effect; "the alkaline inclination of the local waters"; "fabric with a tendency to shrink" [syn: tendency]
8 the act of inclining; bending forward; "an inclination of his head indicated his agreement" [syn: inclining]

User Contributed Dictionary




  1. A tilt or bend
    • The inclination of his head increased and he awoke with a start.
  2. A slant or slope
    • The road up to the house had a steep inclination.
  3. A tendency
    • He had an inclination to drink.
  4. The angle of intersection of a plane and the orbital plane of a planet or moon etc; also the angle between an object's orbit and the ecliptic


A tilt or bend
A slant or slope
A tendency
  • Finnish: taipumus
  • Hebrew:
The angle of intersection of a plane and the orbital plane of a planet or moon
Translations to be checked

Related terms

Extensive Definition

Inclination in general is the angle between a reference plane and another plane or axis of direction. The axial tilt is expressed as the angle made by the planet's axis and a line drawn through the planet's center perpendicular to the orbital plane.


In particular, the inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit. It is the angular distance of the orbital plane from the plane of reference (usually the primary's equator or the ecliptic), normally stated in degrees.
In the solar system, the inclination (i in figure 1, below) of the orbit of a planet is defined as the angle between the plane of the orbit of the planet and the ecliptic —which is the plane containing Earth's orbital path. It could be measured with respect to another plane, such as the Sun's equator or even Jupiter's orbital plane, but the ecliptic is more practical for Earth-bound observers. Most planetary orbits in our solar system have relatively small inclinations, both in relation to each other and to the Sun's equator. There are notable exceptions in the dwarf planets Pluto and Eris, which have inclinations to the ecliptic of 17 degrees and 44 degrees respectively, and the large asteroid Pallas, which is inclined at 34 degrees. Many of the currently known extrasolar planets are in multiple systems, and sometimes have high inclinations.
The inclination of orbits of natural or artificial satellites is measured relative to the equatorial plane of the body they orbit if they do so close enough. The equatorial plane is the plane perpendicular to the axis of rotation of the central body.
  • an inclination of 0 degrees means the orbiting body orbits the planet in its equatorial plane, in the same direction as the planet rotates;
  • an inclination of 90 degrees indicates a polar orbit, in which the spacecraft passes over the north and south poles of the planet; and
  • an inclination of 180 degrees indicates a retrograde equatorial orbit.
For objects farther away from the central body, another reference plane is often used: the Laplace plane. As one moves away from the primary, the Laplace plane starts off in its equatorial plane and then gradually tilts away from that plane until it merges with the primary's orbital plane at great distances.
For objects where the primary's axis of rotation is unknown or poorly known, a satellite's inclination will be given with respect to the ecliptic, or sometimes (for slow-moving objects) with respect to the plane of the sky (see the definition given for binary stars, below).
For the Moon, measuring its inclination with respect to Earth's equatorial plane leads to a rapidly varying quantity and it makes more sense to measure it with respect to the ecliptic (i.e. the plane of the orbit that Earth and Moon track together around the Sun), a fairly constant quantity.

Other meanings

  • For planets and other rotating celestial bodies, the angle of the axis of rotation with respect to the normal to plane of the orbit is sometimes also called inclination, but is better referred to as the axial tilt or obliquity.
  • In particular, for the Earth, the obliquity of the ecliptic is the angle between the plane of the ecliptic and the equator.
  • The inclination of objects beyond the solar system, such as a binary star, is defined as the angle between the normal to the orbital plane (i.e. the orbital axis) and the direction to the observer, since no other reference is available. Equivalently, this can be defined as the angle between the orbital plane and the plane of the sky. The latter depends on the direction in which an observer looks, so one has to be careful when comparing stars in different regions of the celestial sphere. Binary stars with inclinations close to 90 degrees (edge-on) are often eclipsing.
  • The term inclination, can also be used in the context of demonstrating the will of a person regarding a subject.
e.g. "I have neither the time, nor the inclination to talk to you"


In astrodynamics, the inclination i\, can be computed as follows:
inclination in Bulgarian: Инклинация
inclination in Danish: Banehældning
inclination in German: Bahnneigung
inclination in Spanish: Inclinación orbital
inclination in Esperanto: Inklinacio
inclination in Estonian: Inklinatsioon
inclination in French: Inclinaison
inclination in Croatian: Inklinacija
inclination in Italian: Inclinazione (orbita)
inclination in Japanese: 軌道傾斜角
inclination in Hungarian: Inklináció
inclination in Dutch: Glooiingshoek
inclination in Norwegian Nynorsk: Banehelling
inclination in Polish: Inklinacja
inclination in Portuguese: Inclinação
inclination in Russian: Наклонение (астрономия)
inclination in Finnish: Inklinaatio
inclination in Swedish: Inklination
inclination in Slovenian: naklon tira
inclination in Thai: ความเอียงของวงโคจร
inclination in Turkish: Yörünge eğikliği
inclination in Ukrainian: Нахил орбіти
inclination in Chinese: 軌道傾角

Synonyms, Antonyms and Related Words

a thing for, affection, affinity, aim, an ear for, an eye for, angle, angularity, animus, appetence, appetency, appetite, aptitude, aptness, ardor, attitude, azimuth, bag, bank, bearing, bend, bending, bending the knee, bent, bevel, bezel, bias, bob, bow, bowing, bowing and scraping, cant, capacity for, cascade, cast, cataract, character, choice, chosen kind, chute, collapse, comedown, command, conation, conatus, conduciveness, constitution, course, crash, craving, cup of tea, current, curtsy, debacle, decision, declension, declination, defluxion, delight, descending, descension, descent, desire, determination, diathesis, dipping the colors, direction, direction line, discretion, discrimination, disposition, down, downbend, downcome, downcurve, downfall, downflow, downgrade, downpour, downrush, downtrend, downturn, downward trend, drift, drop, dropping, druthers, eagerness, easy slope, eccentricity, enthusiasm, fall, falling, fancy, fascination, favor, favoritism, feeling for, felicity, fervor, flair, fleam, forejudgment, free choice, free will, genius for, gentle slope, genuflection, gift for, glacis, grade, gradient, grain, gravitation, hanging gardens, heading, helicline, helmsmanship, hillside, homage, idiosyncrasy, incline, inclined plane, inclining, individualism, inequality, innate aptitude, intention, interest, involvement, jaundice, jaundiced eye, kidney, kneeling, kowtow, launching ramp, lay, lean, leaning, leaning tower, liability, lie, liking, line, line of direction, line of march, list, longing, lust, make, makeup, making a leg, mental set, mettle, mind, mind-set, mold, mutual affinity, mutual attraction, nature, navigation, nepotism, nod, nodding, obeisance, objective, obsequiousness, one-sidedness, orientation, parti pris, partialism, partiality, particular choice, partisanism, partisanship, passion, penchant, personal choice, piloting, pitch, pleasure, plummeting, point, pounce, preconception, predilection, predisposition, preference, preferential treatment, prejudgment, prejudice, prepossession, presenting arms, probability, proclivity, proneness, propensity, prostration, quarter, rake, ramp, range, rapids, readiness, resolution, reverence, run, salaam, salutation, salute, scarp, scrape, sensitivity to, servility, set, sexual desire, shelving beach, side, slant, slope, soft spot, stamp, standing at attention, steep slope, steerage, steering, stiff climb, stomach, stoop, strain, streak, stripe, style, submission, submissiveness, susceptibility, swag, sway, swoop, sympathy, talus, taste, temper, temperament, tendency, tenor, thing, tilt, tilting, tip, tower of Pisa, track, trend, tropism, turn, turn for, turn of mind, twist, type, undetachment, undispassionateness, unneutrality, velleity, volition, warp, waterfall, way, weakness, will, will power, willingness, wish, zeal
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