Trine
Trine: an aspect comparing two positions through a separation of 120° in ecliptic longitude. This is an angular relationship viewed from Earth, not the physical distance between the bodies.
How it is defined
The exact angle and the allowed tolerance, called the orb, are different quantities. Set the criterion before interpreting. A separation in longitude does not mean the bodies touch or align in all three dimensions.
How to read it
In astrological language this is associated with flow and ease of expression. Its nuance depends on the positions and question, without automatically guaranteeing a favourable or unfavourable outcome.
A concrete example
Geometric example: positions at 10° and 130° have a separation of 120°. A comfortable skill may still remain undeveloped. Notice whether ease becomes practice or inertia.
Explore further
When comparing charts, check the orb and system used. This website’s birth chart provides Sun, Moon and ascendant; this entry explains aspects without adding them to that tool’s results.