英语词源字典 - 在线词源网站

a- (1)[a- 词源字典]: in native (derived from Old English) words, it most commonly represents Old English an "on" (see a (2)), as in alive, asleep, abroad, afoot, etc., forming adjectives and adverbs from nouns; but it also can be Middle English of, as in anew, abreast (1590s); or a reduced form of Old English past participle prefix ge-, as in aware; or the Old English intensive a-, as in arise, awake, ashame, marking a verb as momentary, a single event. In words from Romanic languages, often it represents Latin ad- "to, at."
[I]t naturally happened that all these a- prefixes were at length confusedly lumped together in idea, and the resultant a- looked upon as vaguely intensive, rhetorical, euphonic, or even archaic, and wholly otiose. [OED]
[a- etymology, a- origin, 英语词源]
bramble (n.): Old English bræmbel "rough, prickly shrub" (especially the blackberry bush), with euphonic -b-, from earlier bræmel, from Proto-Germanic *bræmaz (see broom).
empty (adj.): c. 1200, from Old English æmettig "at leisure, not occupied; unmarried," also "containing nothing, unoccupied," from æmetta "leisure," from æ "not" + -metta, from motan "to have" (see might (n.)). The -p- is a euphonic insertion.

Sense evolution from "at leisure" to "containing nothing, unoccupied" is paralleled in several languages, such as Modern Greek adeios "empty," originally "freedom from fear," from deios "fear." "The adj. adeios must have been applied first to persons who enjoyed freedom from duties, leisure, and so were unoccupied, whence it was extended to objects that were unoccupied" [Buck]. Related: Emptier. Figurative sense of empty-nester attested by 1960.
euphony (n.): mid-15c., from Middle French euphonie, from Late Latin euphonia, from Greek euphonia "sweetness of voice," related to euphonos "well-sounding," from eu- "good" (see eu-) + phone "sound, voice," from PIE root *bha- (2) "to speak, tell, say" (see fame (n.)). Related: Euphonic (1782); euphonical (1660s); euphonious (1774). Hence, also, euphonium (1864), the musical instrument.
flavor (n.): c. 1300, "a smell, odor" (usually a pleasing one), from Old French flaor "smell, odor; action of smelling, sense of smell," probably from Vulgar Latin flator "odor," literally "that which blows," in classical Latin "blower," from flare "to blow, puff," which is cognate with Old English blawan (see blow (v.1)).

"Not common before Milton's time" [Century Dictionary], and it is not clear what exactly Milton meant when he used it. The same Vulgar Latin source produced Old Italian fiatore "a bad odor." Sense of "taste, savor" is 1690s, perhaps 1670s; originally "the element in taste which depends on the sense of smell." The -v- in the English word is euphonic or perhaps from influence of savor. Flavor-of-the-month is from 1946 (originally of ice cream).