relative density

English Thesaurus

1. the ratio of the density of something to the density of a standard (noun.attribute)

hypernym	:	denseness, density,
definition	:	the amount per unit size (noun.attribute)

hyponym	:	specific gravity,
definition	:	the density of a substance relative to the density of water (noun.attribute)

hyponym	:	vapor density, vapour density,
definition	:	the density of a gas relative to the density of hydrogen (noun.attribute)