Old English malt (Anglian), mealt (West Saxon), from Proto-Germanic *maltam (cognates: Old Norse malt, Old Saxon malt, Middle Dutch, Dutch mout, Old High German malz, German Malz "malt"), from PIE *meld- (see melt, v.), extended form of root *mel- "soft," probably via notion of "softening" the grain by steeping it in water before brewing. Finnish mallas, Old Church Slavonic mlato are considered to be borrowed from Germanic.

mid-15c., "to convert grain to malt," from malt, n.. Meaning + "to make with malt" is from c.1600. Related: Malted; malting. Malt liquor (which is fermented, not brewed) first attested 1690s. Malted "a drink with malted milk" is from 1945.