tet·rad 
(tĕtrăd′)
(tĕtrăd′)n.
1. A group or set of four.
2. A tetravalent atom, radical, or element.
3. Biology
a. A four-part structure that forms during the prophase of meiosis and consists of two homologous chromosomes, each composed of two sister chromatids.
b. A group of four haploid cells, such as spores, formed by meiotic division of one mother cell.
[Greek tetras, tetrad-; see kwetwer- in the Appendix of Indo-European roots.]
te·tradic adj.
- biolytic
- biomagnetism
- biomagnification
- biomarker
- biomass
- biomaterial
- biomathematical
- biomathematician
- biomathematics
- biome
- biomechanical
- biomechanically
- biomechanics
- biomedical
- biomedical engineering
- biomedicine
- biometeorology
- biometric
- biometrical
- biometrically
- biometrics
- biometry
- biomorph
- biomorphic
- biomorphism