Meaning
A special sign position for a planet — stronger than its own sign, weaker than exaltation — in a specific degree range.
Etymology
Sanskrit mūla (root) + trikoṇa (trine) — the 'root trine' sign, a special sign position stronger than own-sign but weaker than exaltation.
Detailed Explanation
Mūlatrikoṇa is an intermediate dignity in Vedic astrology — between exaltation and own sign. Each planet has one mūlatrikoṇa sign (or range of degrees within a sign). The scale of dignity from strongest to weakest is: Exaltation > Mūlatrikoṇa > Own sign > Friendly sign > Neutral sign > Enemy sign > Debilitation. Mūlatrikoṇa positions: Sun 0–20° Leo, Moon 4–20° Taurus, Mars 0–12° Aries, Mercury 16–20° Virgo, Jupiter 0–10° Sagittarius, Venus 0–15° Libra, Saturn 0–20° Aquarius. The concept is primarily used in shadbala (six-fold strength) calculations.