It comes from the Greek word "τέσσαρες" (téssares), which means "four".
Here are some examples of words using the prefix "tetra":
* Tetrad: A group of four.
* Tetragon: A four-sided polygon.
* Tetrahedron: A solid with four triangular faces.
* Tetrameter: A line of poetry with four metrical feet.
* Tetracycline: A group of antibiotics.