Reference library

I Ching Glossary

Use this glossary to pin down the core terms that recur in the I Ching: line states, trigrams, hexagrams, changing lines, and the distinction between primary and changed figures.

Updated April 1, 2026Produced by MahjongHouse

In short

The glossary exists to turn recurring I Ching terms into short, self-contained answers that can be read directly, linked internally, and cited cleanly.

Diagram showing the relationship between yin and yang, trigrams, hexagrams, changing lines, and the move from a primary hexagram to a changed hexagram.
The glossary terms are easiest to learn as one connected system: line states form trigrams, trigrams form hexagrams, and changing lines create movement between figures.
Yin and Yang in the I Ching

In the I Ching, yin and yang are the two line states from which every trigram and hexagram is built: yin is open, and yang is solid.

What a Trigram Is in the I Ching

A trigram is a three-line figure built from yin and yang lines. In the I Ching, eight trigrams form the base layer from which the sixty-four hexagrams are made.

What the Primary Hexagram Means

The primary hexagram is the first six-line figure produced by a cast. It describes the present pattern, condition, or structure surrounding the question.

What the Changed Hexagram Means

The changed hexagram is the second figure formed by flipping every changing line in the primary hexagram. It shows where the pattern is moving.

What the Bagua Are in the I Ching

The bagua are the eight trigrams of the I Ching. Together they form the basic map from which the sixty-four hexagrams are assembled.