"quality of being skew," 1877, from skew (adj.) + -ness.
Entries linking to skewness
skew v.
c. 1400, "turn aside, take an oblique course, run obliquely or at an angle," also "escape," intransitive senses now archaic or obsolete, from Old North French eskiuer "shy away from, avoid," Old French eschiver (see eschew; also compare shy (adj.)).
The transitive sense of "turn (something) aside, give oblique direction to" is attested from 1570s. The meaning "depict unfairly" is recorded by 1872, on notion of being "give oblique direction to," hence "to distort, to make slant"(compare bias, also an image of obliqueness). The statistical sense dates from 1929. Related: Skewed; skewing.
The adjectival meaning "slanting, turned to one side" is recorded from c. 1600, from the verb; the noun meaning "a slant, a deviation" is attested by 1680s.
-ness
word-forming element denoting action, quality, or state, attached to an adjective or past participle to form an abstract noun, from Old English -nes(s), from Proto-Germanic *in-assu- (cognates: Old Saxon -nissi, Middle Dutch -nisse, Dutch -nis, Old High German -nissa, German -nis, Gothic -inassus), from *-in-, originally belonging to the noun stem, + *-assu-, abstract noun suffix, probably from the same root as Latin -tudo (see -tude).