acreyoudaoicibaDictYouDict[acre 词源字典]
acre: [OE] Acre is a word of ancient ancestry, going back probably to the Indo-European base *ag-, source of words such as agent and act. This base had a range of meanings covering ‘do’ and ‘drive’, and it is possible that the notion of driving contributed to the concept of driving animals on to land for pasture. However that may be, it gave rise to a group of words in Indo- European languages, including Latin ager (whence English agriculture), Greek agros, Sanskrit ájras, and a hypothetical Germanic *akraz.

By this time, people’s agricultural activities had moved on from herding animals in open country to tilling the soil in enclosed areas, and all of this group of words meant specifically ‘field’. From the Germanic form developed Old English æcer, which as early as 1000 AD had come to be used for referring to a particular measured area of agricultural land (as much as a pair of oxen could plough in one day).
=> act, agent, agriculture, eyrie, onager, peregrine, pilgrim[acre etymology, acre origin, 英语词源]
acre (n.)youdaoicibaDictYouDict
Old English æcer "tilled field, open land," from Proto-Germanic *akraz "field, pasture" (cognates: Old Norse akr, Old Saxon akkar, Old Frisian ekker, Middle Dutch acker, Dutch akker, Old High German achar, German acker, Gothic akrs), from PIE *agro- "field" (cognates: Latin ager "field, land," Greek agros, Sanskrit ajras "plain, open country").

Originally in English without reference to dimension; in late Old English the amount of land a yoke of oxen could plow in a day, afterward defined by statute as a piece 40 poles by 4, or an equivalent shape (5 Edw. I, 31 Edw. III, 24 Hen. VIII). Original sense retained in God's acre "churchyard."