Astrology glossary.

Ascendant

calculation

The ecliptic degree rising on the eastern horizon for a specified time and place. Astrology also calls it the rising sign and assigns it interpretive meaning.

Aspect

convention

An angular separation between two chart points. Conjunctions, oppositions, trines, squares, and sextiles are common astrological categories; the accepted orb is a declared convention.

Birth chart

mixed

A diagram of calculated celestial positions for a person's birth time and place, also called a natal chart. Interpretive meaning belongs to astrological practice.

Chart ruler

convention

In astrology, the planet ruling the Ascendant's sign. Its interpretive importance is a traditional convention, not an astronomical measurement.

Ecliptic

astronomy

The apparent annual path of the Sun on the celestial sphere and the reference plane commonly used for zodiacal longitude.

Ephemeris

astronomy

A table or computational system giving predicted positions of celestial bodies at specified times.

Horary astrology

convention

An astrological practice that interprets a chart cast for the time and place a specific question is received or understood.

House

mixed

One of twelve chart sectors derived from the local horizon and meridian under a selected house system. Sector boundaries are calculated; assigned life topics are astrological conventions.

House cusp

mixed

The calculated boundary that begins an astrological house. Different house systems can produce different intermediate cusps.

Local sidereal time

astronomy

A measure tied to Earth's rotation and the local meridian, used when relating celestial coordinates to a location's horizon.

Midheaven

mixed

The ecliptic point associated with the local meridian, commonly abbreviated MC. Astrology assigns it themes such as public role or vocation.

Natal chart

mixed

Another name for a birth chart: celestial positions calculated for a stated birth moment and location, displayed for astrological interpretation.

Orb

convention

The permitted deviation from an aspect's exact angle. Orb limits vary by astrological method and should be stated explicitly.

Planetary longitude

astronomy

A body's angular position measured along the ecliptic from the reference origin, usually expressed from 0° to 360° or by sign and degree.

Retrograde

mixed

Apparent backward motion against the star background as seen from the chosen observational frame; astrology assigns additional symbolic interpretations.

Rising sign

mixed

The zodiac sign containing the Ascendant. It depends strongly on time and place and should not be claimed as exact when birth time is unknown.

Sign

mixed

In tropical astrology, one of twelve equal 30° divisions of the ecliptic. Zodiac signs are not the same as the unequal astronomical constellations.

Significator

convention

In horary and other traditional astrology, a planet or point selected to represent a person, topic, or matter in the judgment.

Transit

mixed

A current or selected-time planetary position compared with another chart or interpreted on its own. The position is calculated; its meaning is astrological.

Zodiac

mixed

A band around the ecliptic. Astrology divides it into twelve signs; astronomy recognizes constellations along the ecliptic as distinct sky regions.

Sources and editorial rule

Astronomical definitions are aligned with the U.S. Naval Observatory’s celestial-coordinate reference, the International Astronomical Union’s constellation guidance, and Swiss Ephemeris documentation. Astrological interpretations and category rules are labeled as conventions rather than scientific findings.

If a definition is unclear or inaccurate, use the corrections process. For implementation details, see methodology.