Etymology: In sense 1 < Middle French quaterne pamphlet, register, quire (a1410) and its etymon post-classical Latin quaternus (also quaternum) booklet, quire (frequently from 12th cent. in British and continental sources), use as singular noun of classical Latin quaternus , singular form corresponding to quaternī four each, set of four (see quatern adj.); compare earlier quire n. In sense 2 reborrowed < French quaterne set of four numbers in a lottery drawn at the same time, (also) four lottery numbers lined up horizontally (1786; compare earlier use with reference to a throw of dice (13th cent. in Old French)) < classical Latin quaternus.It is uncertain whether the following is to be interpreted as showing an earlier attestation of the word in Middle English (in sense 1) or a use in Anglo-Norman (since the form is abbreviated, it could also represent an early use of quaternion n.):1352 in E. W. Brayley & J. Britton Hist. Palace Westminster (1836) 183 [To John Lambard, for two] quatern' [of royal paper for the painter's] patrons [1s. 8d].

Etymology: < classical Latin quaternī four each, four at a time, set of four, four < quater four times (see quatercentenary adj. and n.) + -nī , suffix forming distributive numerals, plural of -nus , suffix forming adjectives. Compare earlier quatrefoil adj. and slightly earlier quaternate adj.