[mem.o.ran.dum] n, pl -dums or -da [ME, to be remembered, fr. L, neut. of memorandus, gerundive of memorare] (ca. 1543) 1: an informal record; also: a written reminder
2: an informal written note of a transaction or proposed instrument 3 a: an informal diplomatic communication b: a usu. brief communication written for interoffice circulation c: a communication that contains directive, advisory, or informative matter usage Although some commentators warn against the use of memoranda as a singular and condemn the plural memorandas, our evidence indicates that these forms are rarely encountered in print. We have a little evidence of the confusion of forms, including use of memorandum as a plural, in speech (as at congressional hearings). As plurals memoranda and memorandums are about equally frequent.