attendyoudaoicibaDictYouDict[attend 词源字典]
attend: [13] Etymologically, attend means ‘stretch to’. It comes originally from Latin attendere, a compound verb formed from the prefix ad- ‘to’ and tendere ‘stretch’ (a descendant of an Indo-European base *ten-, *ton- ‘stretch’ which also produced, among others, Latin tenēre ‘hold’ – source of English contain, maintain, obtain, etc – and English tendon, thin, and tone).

By metaphorical extension ‘stretch to’ became ‘direct one’s attention to’, which was the original meaning of the verb in Old French atendre and subsequently in English. The sense ‘take care of’ developed in the 15th century, ‘be present’ much later, in the 17th century. The noun derivative attention [14] comes from Latin attentiō. Tend meaning ‘look after’ comes mainly from attend, but also partly from intend, in both cases with loss of the first syllable.
=> contain, maintain, obtain, tendon, thin, tone[attend etymology, attend origin, 英语词源]
attend (v.)youdaoicibaDictYouDict
c. 1300, "to direct one's mind or energies," from Old French atendre (12c., Modern French attendre) "to expect, wait for, pay attention," and directly from Latin attendere "give heed to," literally "to stretch toward," from ad- "to" (see ad-) + tendere "stretch" (see tenet). The notion is of "stretching" one's mind toward something. Sense of "take care of, wait upon" is from early 14c. Meaning "to pay attention" is early 15c.; that of "to be in attendance" is mid-15c. Related: Attended; attending.