slow (adj.)youdaoicibaDictYouDict
Old English slaw "inactive, sluggish, torpid, lazy," also "not clever," from Proto-Germanic *slæwaz (cognates: 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"). Meaning "taking a long time" is attested from early 13c. Meaning "dull, tedious" is from 1841. As an adverb c. 1500. The slows "imaginary disease to account for lethargy" is from 1843.