a compound derived from ammonium with hydrogen atoms replaced by organic groups; used as surface-active agents, disinfectants, and in drugs
consisting of or especially arranged in sets of four
the cardinal number that is the sum of three and one
last 2 million years
put or add together
a whole formed by a union of two or more elements or parts
(chemistry) a substance formed by chemical union of two or more elements or ingredients in definite proportion by weight
an enclosure of residences and other building (especially in the Orient)
