Tetrad ('group of 4') or tetrade may refer to:
Tetrad (area), an area 2 km x 2 km square
Tetrad (astronomy), four total lunar eclipses within two years
Tetrad (chromosomal formation)
Tetrad (general relativity), or frame field
Tetrad formalism, an approach to general relativity
Tetrad (geometry puzzle), a set of four simply connected disjoint planar regions in the plane
Tetrad (meiosis), the four cells produced by meiotic cell division
Tetrad (music), a set of four notes
Tetrad (symbol), or tetractys, a triangular figure of ten points arranged in four rows, and mystical symbol
Medical tetrad, a group of four signs or symptoms which characterise a specific medical condition
Nibble, or tetrade, a 4-bit group
a tuple of length 4
Tetrad Islands, in the Antarctic
