abhor (v.) Look up abhor at Dictionary.com
mid-15c., from Latin abhorrere "shrink back from, have an aversion for, shudder at," from ab- "away" (see ab-) + horrere "tremble at, shudder," literally "to bristle, be shaggy," from PIE *ghers- "start out, stand out, rise to a point, bristle" (see horror).

The notion is "shrink back" with horror or dread, hence "regard with repugnance, loathe." Formerly also "fill (someone) with horror or loathing" (16c.). In Latin it was less intense: "be remote from, vary from, differ from, be out of harmony with." Related: Abhorred; abhorring.