Astrology Glossary
Clear, concise definitions for key astronomical and astrological terms used across our calculator and educational guides.
Ascendant (Rising Sign)
The degree of the zodiac sign ascending on the eastern horizon at the moment and location of birth. It marks the cusp of the 1st House in a birth chart.
Ayanamsa
The angular difference between the Vernal Equinox (Tropical Zodiac) and the actual constellations (Sidereal Zodiac), currently around 24 degrees.
Big Three
The trio of Sun Sign, Moon Sign, and Rising Sign, which together form the core foundation of personality interpretation in Western astrology.
Cardinal Signs
Aries, Cancer, Libra, and Capricorn — the four zodiac signs that mark the beginning of seasons, associated with initiative, action, and leadership.
Chart Ruler
The planet that rules the zodiac sign of the Ascendant. For example, if your Ascendant is Taurus, your chart ruler is Venus.
Cusp
The boundary dividing two zodiac signs or house divisions in a birth chart.
Descendant (DC)
The point directly opposite the Ascendant on the western horizon, marking the cusp of the 7th House (partnerships and one-on-one relationships).
Ecliptic
The apparent path of the Sun across the sky throughout the year, along which the zodiac signs are measured.
Ephemeris
A table or mathematical software library (such as the Swiss Ephemeris) providing the exact astronomical positions of celestial bodies at any given time.
Fixed Signs
Taurus, Leo, Scorpio, and Aquarius — the four zodiac signs that occur in the middle of seasons, associated with persistence, stability, and focus.
Imum Coeli (IC)
The bottom-most point of the birth chart, representing private roots, home, family, and inner emotional foundation.
Julian Day
A continuous count of days since the beginning of the Julian Period (Jan 1, 4713 BC), used by astronomers to compute precise planetary motion.
Medium Coeli (MC / Midheaven)
The highest point of the ecliptic in the birth chart, traditionally associated with career, public reputation, and aspirations.
Mutable Signs
Gemini, Virgo, Sagittarius, and Pisces — the four zodiac signs that end seasons, associated with adaptability, change, and flexibility.
Placidus House System
The most widely used house division system in Western astrology, which divides time between the horizon and meridian into equal portions.
Sidereal Zodiac
The zodiac system based on the fixed physical constellations, primarily used in Vedic (Jyotish) astrology.
Tropical Zodiac
The zodiac system based on the seasons, beginning 0° Aries at the Vernal Equinox, primarily used in Western astrology.