Definitions

1. noun

A set of four things

“The tetrad of planets in our solar system include Mercury, Venus, Earth, and Mars.”

2. noun

In music, a group of four notes or chords repeated in a pattern

“The composer used a tetrad to create a sense of rhythm in the symphony.”

3. noun

In poetry, a stanza or verse consisting of four lines

“The poet wrote a tetrad to express her emotions and thoughts.”

4. noun

A set of four items used to identify or classify something

“The tetrad of characteristics included size, color, shape, and weight.”