slowness (n.)

Middle English slou, from Old English slaw "inactive by nature, sluggish, torpid, lazy, tardy in taking action," also "not clever, dull, not quick in comprehension," from Proto-Germanic *slæwaz (source also of Old Saxon sleu "blunt, dull," Middle Dutch slee, Dutch sleeuw "sour, tart, blunt," Old High German sleo "blunt, dull," Old Norse sljor, Danish sløv, Swedish slö "blunt, dull").

The meaning "taking a long time to develop, not happening in a short time" is attested from c. 1200; that of "not quick to move physically, taking a long time to move or go a short distance" is by mid-14c. The meaning "dull, tedious" is from 1841. Of clocks, from 1690s.

As an adverb c. 1500. As a noun from c.122, "the slothful, sluggards." The slows "imaginary disease to account for lethargy" is from 1843. Slow-paced "moving or advancing slowly" is from 1590s. Slow-motion (adj.) in cinematography is by 1929.

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).