(1) Formation of a sediment at the bottom of a liquid. (2) SYN: hypostatic congestion. (3) The phenomenon whereby the phenotype that would ordinarily be manifested at one locus is obscured by the genotype at another epistatic locus; e.g., in humans, the phenotype for the ABO blood group locus can be expressed only in the presence of its precursor, H substance. The Bombay factor in the homozygous state blocks H formation and obscures the ABO phenotype. [G. hypo-stasis, a standing under, sediment]
