: 11 The later definition by Cavalli-Sforza & Bodmer (1971) is currently used: Genetic polymorphism is the occurrence in the same population of two or more alleles at one locus, each with appreciable frequency, where the minimum frequency is typically taken as 1%.
The financial world splits up its calendar into four quarters, each three months long. If January to March is the first quarter, April to June is the second quarter, and so on, though a company's first quarter does not have to begin in January.
It divides the academic year into four quarters, each of which is usually 12 weeks long. Three of the four quarters (Autumn/Fall, Winter, and Spring, operating from September until June or from August until May) are thus equivalent to two 18-week semesters.