Entries linking to fewness
Old English feawe (plural; contracted to fea) "not many, a small number; seldom, even a little," from Proto-Germanic *fawaz (source also of Old Saxon fa, Old Frisian fe, Old High German fao, Old Norse far, Danish faa), from PIE root *pau- (1) "few, little."
Always plural in Old English, according to OED "on the analogy of the adverbial fela," meaning "many." Phrase few and far between attested from 1660s. Unusual ironic use in quite a few "many" (1854), earlier a good few (1803).
There is likewise another dialectical use of the word few among them [i.e. "the Northern Counties"], seemingly tending to its total overthrow; for they are bold enough to say—"a good few," meaning a good many. [Samuel Pegge, "Anecdotes of the English Language," London, 1803]
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).