attend – присутствовать, посещать, ходить, следить.

attend (v.) (направлять чьи-то помыслы или энергию; из старофранцузского «atendre» - ожидать, обращать внимание; из латинского «attendre» - обращать внимание, в литературном языке – дотянуться (протянуть). Из слова «tendere» - натягивать
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.

tend (v.2)
"attend to," early 14c., a shortening of Middle English atenden (see attend).

tenet (n.) (догмат, принцип). Из латинского «tenet» - он держал; из «tenere» - держать, поддерживать.
"principle," properly "a thing held (to be true)," early 15c., from Latin tenet "he holds," third person singular present indicative of tenere "to hold, to keep, to maintain" from PIE root *ten- "to stretch" (cf. Sanskrit tantram "loom," tanoti "stretches, lasts;" Persian tar "string;" Lithuanian tankus "compact," i.e. "tightened;" Greek teinein "to stretch," tasis "a stretching, tension," tenos "sinew," tetanos "stiff, rigid," tonos "string," hence "sound, pitch;" Latin tendere "to stretch," tenuis "thin, rare, fine;" Old Church Slavonic tento "cord;" Old English thynne "thin"). Connection notion between "stretch" and "hold" is "to cause to maintain." The modern sense is probably because tenet was used in Medieval Latin to introduce a statement of doctrine.

attendant (n.)
1550s, "one who waits upon," from the adjective, or from Middle French atendant, noun use of present participle of atendre (see attend).

attendee (n.)
"one who attends" (something), 1961, from attend + -ee. Attender is older (mid-15c.) but had senses "one who waits upon" and "one who gives heed."

attendance (n.)
late 14c., "act of attending to one's duties," from Old French atendance "attention, wait, hope, expectation," from atendant, present participle of atendre (see attend). Meaning "action of waiting on someone" dates from late 14c. (to dance attendance on someone is from 1560s); that of "action of being present, presenting oneself" (originally with intent of taking a part) is from mid-15c. Meaning "number of persons present" is from 1835.

Как видите, все одно и то же. PIE корень *ten – тянуть, протягивать. Опять русское слово «тянуть». См. «attach». Интересно, откуда они взяли староцерковнославянское «tento» - веревка?

attention – внимание. To pay attention – обращать внимание. Это опять русское «тянуть». Точнее «дотянуть». См. предыдущие слова.

attention (n.)
late 14c., "giving heed," from Latin attentionem (nominative attentio) "attention, attentiveness," noun of action from past participle stem of attendere "mental heeding" (see attend). Used with a remarkable diversity of verbs (e.g. pay, gather, attract, draw, call). As a military cautionary word preparative to giving a command, it is attested from 1792.

Кстати, немецкое «achtung» из этой же компании.
achtung
German word used to command attention, from German achtung, from acht (n.) "attention, care, heed, consideration," achten (v.) "pay attention to, regard, esteem, respect," from Old High German ahton "pay attention to," a general Germanic word akin to Old English eahtian "to estimate, esteem, consider, praise," but with no living native descendants in English.