lineyoudaoicibaDictYouDict[line 词源字典]
line: [OE] The closest modern English line comes to its ancestor is probably in the fisherman’s ‘rod and line’ – a ‘string’ or ‘chord’. For it goes back to Latin līnea ‘string’. This was a derivative of līnum ‘flax’ (source of English linen), and hence meant etymologically ‘flaxen thread’. English acquired it in two separate phases.

First of all it was borrowed directly from Latin in the Old English period, and then it made a return appearance via Old French ligne in the 14th century; the two have coalesced to form modern English line. Derived forms include lineage [14], lineal [15], lineament [15], and liner [19]. The last is based on the sense ‘shipping line’, which goes back to the notion of a ‘line’ or succession of ships plying between ports.
=> align, lineal, linen, liner[line etymology, line origin, 英语词源]
line (n.)youdaoicibaDictYouDict
a Middle English merger of Old English line "cable, rope; series, row, row of letters; rule, direction," and Old French ligne "guideline, cord, string; lineage, descent;" both from Latin linea "linen thread, string, line," from phrase linea restis "linen cord," from fem. of lineus (adj.) "of linen," from linum "linen" (see linen).

Oldest sense is "rope, cord, string;" extended late 14c. to "a thread-like mark" (from sense "cord used by builders for making things level," mid-14c.), also "track, course, direction." Sense of "things or people arranged in a straight line" is from 1550s. That of "cord bearing hooks used in fishing" is from c. 1300. Meaning "one's occupation, branch of business" is from 1630s, probably from misunderstood KJV translation of 2 Cor. x:16, "And not to boast in another mans line of things made ready to our hand," where line translates Greek kanon, literally "measuring rod." Meaning "class of goods in stock" is from 1834. Meaning "telegraph wire" is from 1847 (later "telephone wire").

Meaning "policy or set of policies of a political faction" is 1892, American English, from notion of a procession of followers; this is the sense in party line. In British army, the Line (1802) is the regular, numbered troops, as distinguished from guards and auxiliaries. In the Navy (1704, as in ship of the line) it refers to the battle line. Lines "words of an actor's part" is from 1882. Lines of communication were originally transverse trenches in siegeworks.
line (v.1)youdaoicibaDictYouDict
"to cover the inner side of," late 14c., from Old English lin "linen cloth" (see linen). Linen was frequently used in the Middle Ages as a second layer of material on the inner side of a garment. Related: Lined; lining.
line (v.2)youdaoicibaDictYouDict
late 14c., "to tie with a cord," from line (n.). Meaning "to mark or mark off with lines" is from mid-15c. Sense of "to arrange in a line" is from 1640s; that of "to join a line" is by 1773. To line up "form a line" is attested by 1889, in U.S. football.