rankyoudaoicibaDictYouDict[rank 词源字典]
rank: English has two words rank. The one meaning ‘row, line’ [16], and hence ‘position of seniority’, was borrowed from Old French ranc (source also of English range), which goes back via Frankish *hring to a prehistoric Germanic *khrengaz ‘circle, ring’ (ancestor of English ring). Rank ‘absolute, downright’ [OE], as in ‘rank bad manners’, has had an eventful semantic history.

It originally meant ‘haughty’ and ‘full-grown’, and came from a prehistoric Germanic *rangkaz, which also produced Old Norse rakkr ‘erect’. ‘Full-grown’ evolved via ‘growing vigorously, luxuriant’ (which still survives) into ‘gross, disgusting’, on which the present-day intensive usage is based.
=> range, ring[rank etymology, rank origin, 英语词源]
rank (v.)youdaoicibaDictYouDict
1570s, "arrange in lines;" 1590s, "put in order, classify; assign a rank to," from rank (n.). Related: Ranked; ranking.
rank (n.)youdaoicibaDictYouDict
early 14c., "row, line series;" c. 1400, a row of an army, from Old French renc, ranc "row, line" (Modern French rang), from Frankish *hring or some other Germanic source (compare Old High German hring "circle, ring"), from Proto-Germanic *hringaz "circle, ring, something curved" (see ring (n.1)).

Meaning "a social division, class of persons" is from early 15c. Meaning "high station in society" is from early 15c. Meaning "a relative position" is from c. 1600.
rank (adj.)youdaoicibaDictYouDict
Old English ranc "proud, overbearing, showy," from Proto-Germanic *rankaz (cognates: Danish rank "right, upright," German rank "slender," Old Norse rakkr "straight, erect"), perhaps from PIE *reg- "to stretch, straighten" (see right (adj.)). In reference to plant growth, "vigorous, luxuriant, abundant, copious" it is recorded from c. 1300. Related: Rankly; rankness.

Sense evolved in Middle English to "large and coarse" (c. 1300), then, via notion of "excessive and unpleasant," to "corrupt, loathsome, foul" (mid-14c.), perhaps from influence of Middle French rance "rancid." In 17c. also "lewd, lustful."

Much used 16c. as a pejorative intensive (as in rank folly). This is possibly the source of the verb meaning "to reveal another's guilt" (1929, underworld slang), and that of "to harass, abuse," 1934, U.S. black dialect, though this also may be from the role of the activity in establishing social hierarchy (from rank (n.)).