Hypoploid
A genetic condition in which a chromosome or segment of a chromosome is underrepresented in the genotype. Opposite: hyperploid.

Hypostatic; hypostasis
See epistasis.

Hypothalamic peptides
Peptides generated in the vertebrate forebrain and concerned with regulating the body’sphysiological state.

Hysteresis (magnetic)
The irreversible magnetic fluxdensity versus magnetic field strength (B versus H) behavior found for ferromagnetic and ferromagnetic materials.