Source : Webster's Revised Unabridged Dictionary (1913)

Lank \Lank\, a. [Compar. {Lanker}; superl. {Lankest}.] [{AS}.
   hlanc; cf. G. lenken to turn, gelenk joint, OHG. hlanca hip,
   side, flank, and E. link of a chain.]
   1. Slender and thin; not well filled out; not plump;
      shrunken; lean.

            Meager and lank with fasting grown.   --Swift.

            Who would not choose . . . to have rather a lank
            purse than an empty brain?            --Barrow.

   2. Languid; drooping.[Obs.]

            Who, piteous of her woes, reared her lank head.
                                                  --Milton.

   {Lank hair}, long, thin hair. --Macaulay.

Lank \Lank\, v. i. & t.
   To become lank; to make lank. [Obs.] --Shak. --G. Fletcher.

Source : WordNet®

lank
     adj 1: long and thin and often limp; "grown lank with fasting";
            "lank mousy hair"
     2: long and lean [syn: {spindly}]