SEM'IBREVE, [semi and breve; formerly written semibref.] In music, a note of half the duration of time of the breve. It is the measure note by which all others are regulated. It contains the time of two minims, four crotchets, eights quavers, sixteen semiquavers and thirty-two demisemiquavers.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI