lank adj.

late Old English flanc "flank, fleshy part of the side," from Old French flanc "hip, side," from Frankish or another Germanic source, from Proto-Germanic *hlanca- (source also of Old High German (h)lanca, Middle High German lanke "hip joint," German lenken "to bend, turn aside;" Old English hlanc "loose and empty, slender, flaccid;" Old Norse hlykkr "a bend, noose, loop"), from PIE root *kleng- "to bend, turn" (see link (n.)). Showing characteristic change of Germanic hl- to Romanic fl-. The military sense is first attested 1540s. Meaning "side" of anything is by 1620s. As an adjective, "pertaining to the flank or side," 1660s. Related: Flanked; flanking.

1630s, "straight and flat," used of hair, from lank (adj.) + -y (2). Sense of "awkwardly tall and thin" is first recorded 1818. Fowler writes that "The short form is almost only literary, the long chiefly colloquial." Related: Lankily (1848); lankiness (1846).

early 15c., "one of a series of rings or loops which form a chain; section of a cord," probably from Old Norse *hlenkr or a similar Scandinavian source (compare Old Norse hlekkr "link," in plural, "chain;" Old Swedish lænker "chain, link," Norwegian lenke "a link," Danish lænke "a chain," German Gelenk "articulation, a joint of the body; a link, ring"), from Proto-Germanic *khlink- (source also of German lenken "to bend, turn, lead"), from PIE root *kleng- "to bend, turn." Related to lank, flank, flinch.

The noun is not found in Old English, where it is represented by lank "the hip" ("turn of the body"), hlencan (plural) "armor." Meaning "a division of a sausage made in a continuous chain" is from mid-15c. Meaning "anything serving to connect one thing or part with another" is from 1540s. Sense of "means of telecommunication between two points" is from 1911. Missing link between man and apes dates to 1880.