"grain (usually barley) in which, by heat, the starch is converted to sugar," Old English malt (Anglian), mealt (West Saxon), from Proto-Germanic *maltam (source also of Old Norse malt, Old Saxon malt, Middle Dutch, Dutch mout, Old High German malz, German Malz "malt"), possibly from PIE root *mel- (1) "soft" via the notion of "softening" the grain by steeping it in water before brewing.
By the addition of hops, and the subsequent processes of cooling, fermentation, and clarification, the wort is converted into porter, ale, or beer. The alcoholic fermentation of the wort without the addition of hops and distillation yield crude whisky. [Century Dictionary]
Finnish mallas, Old Church Slavonic mlato are considered to be borrowed from Germanic. Meaning "liquor produced by malt" is from 1718. As an adjective, "pertaining to, containing, or made with malt," 1707; malt liquor (which is fermented, not brewed) is attested from 1690s.
c. 1200, likur "any matter in a liquid state, a liquid or fluid substance," from Old French licor "fluid, liquid; sap; oil" (12c., Modern French liqueur), from Latin liquorem (nominative liquor) "a liquid, liquor; wine; the sea," originally "liquidity, fluidity," from liquere "be fluid, liquid" (see liquid (adj.)).
Narrowed sense of "fermented or distilled drink" (especially wine) first recorded c. 1300; the broader sense seems to have been obsolete from c. 1700. As long as liquor is in him was a Middle English expression, "as long as he is alive," that is, "as long as he has a drop of blood left." The form in Modern English has been assimilated to Latin, but the old pronunciation persists.
mid-15c., malten, "to convert grain to malt," from malt (n.). Meaning "to make with malt" is from c. 1600. Related: Malted; malting. Malted (n.) "a drink with malted milk" is by 1945.
c. 1500, "to moisten," from liquor (n.). From 1550s as "supply with liquor," 1839 as "drink" (intoxicating liquor). To liquor up "get drunk" is from 1845. Related: Liquored; liquoring.
"strong drink of any kind," especially malt liquor, 1670s, perhaps imitative of the sound of drinking.
"intoxicating liquor made by malt fermentation," Old English ealu "ale, beer," from Proto-Germanic *aluth- (source also of Old Saxon alo, Old Norse öl), which is of uncertain origin. Perhaps from a PIE root meaning "bitter" (source also of Latin alumen "alum"), or from PIE *alu-t "ale," from root *alu-, which has connotations of "sorcery, magic, possession, and intoxication" [Watkins]. The word was borrowed from Germanic into Lithuanian (alus) and Old Church Slavonic (olu).
In the fifteenth century, and until the seventeenth, ale stood for the unhopped fermented malt liquor which had long been the native drink of these islands. Beer was the hopped malt liquor introduced from the Low Countries in the fifteenth century and popular first of all in the towns. By the eighteenth century, however, all malt liquor was hopped and there had been a silent mutation in the meaning of the two terms. For a time the terms became synonymous, in fact, but local habits of nomenclature still continued to perpetuate what had been a real difference: 'beer' was the malt liquor which tended to be found in towns, 'ale' was the term in general use in the country districts. [Peter Mathias, "The Brewing Industry in England," Cambridge University Press, 1959]
Meaning "festival or merry-meeting at which much ale was drunk" was in Old English (see bridal).
"barley," late 14c., from barley + corn (n.1). Perhaps to distinguish the barley plant or the grain from its products. In Britain and U.S., the grain is used mainly to prepare liquor, hence personification of malt liquor as John Barleycorn (1620) in popular ballads, and many now-obsolete figures of speech, such as to wear a barley cap (16c.) "to be drunk."
Middle English bolken, from Old English bealcan "bring up wind from the stomach," also "swell, heave," of echoic origin (compare Dutch balken "to bray, shout"). It was extended to volcanoes, cannons, etc. 1570s. Related: Belched; belching. As a noun, "an act of belching," it is recorded from 1510s; also slang for "poor beer, malt liquor" (1706).