loafyoudaoicibaDictYouDict[loaf 词源字典]
loaf: English has two words loaf. By far the older is ‘portion of bread’ [OE], which goes back to a prehistoric Germanic *khlaibaz. This also produced German laib and Danish lev ‘loaf’, and was borrowed, originally into Gothic, from an Old Slavic chleb (source of modern Russian and Polish chleb ‘bread, loaf’). Heavily disguised, loaf forms part of both lady and lord (which etymologically mean respectively ‘loafkneader’ and ‘loaf-guardian’), and it also contributed the first syllable to Lammas [OE], literally ‘loaf-mass’.

The verb loaf ‘dawdle, mooch’ [19] seems to have been a back-formation from loafer, which was probably adapted in 19th-century American English from German landläufer ‘vagabond’, a compound of land ‘land’ and läufer ‘runner’ (to which English leap is related).
=> lady, lord; leap[loaf etymology, loaf origin, 英语词源]
loaf (n.)youdaoicibaDictYouDict
late 13c., from Old English hlaf "portion of bread baked in a mass of definite form," from Proto-Germanic *khlaibuz (cognates: Old Norse hleifr, Swedish lev, Old Frisian hlef, Old High German hleib, German Laib, Gothic hlaifs "bread, loaf"), of uncertain origin, perhaps connected to Old English hlifian "to raise higher, tower," on the notion of the bread rising as it bakes, but it is unclear whether "loaf" or "bread" is the original sense. Finnish leipä, Old Church Slavonic chlebu, Lithuanian klepas probably are Germanic loan words. Meaning "chopped meat shaped like a bread loaf" is attested from 1787.
loaf (v.)youdaoicibaDictYouDict
1835, American English, back-formation from loafer (1830). Related: Loafed; loafing.
The term "loafing" is, of course, very vague. Its meaning, like that of its opposite, "work," depends largely on the user. The highly successful quarterback with an E in Greek is a loafer in his professor's eyes, while the idea of the professor's working, in spite of his voluminous researches on Mycenean Table Manners, would excite hoots of derision from the laborer that lays the drains before his study window. [Yale Literary Magazine, May 1908]