Definition of "lankiness"

In his civil dress his lankiness and length of limb gave him an awkward appearance, but on horse-back, with his lean, gaunt face looking out from his steel cap, his breastplate and buff jacket filling out his figure, and his high boots of untanned leather reaching to the centre of his thighs, he looked the veteran man-at-arms.

1888, Sir Arthur Conan Doyle, chapter 8, in Micah Clarke