Taken from combining both the words horrible and terrible:

adj.
Arousing or tending to arouse horror; dreadful: “War is beyond all words herrible” (Winston S. Churchill).
Very unpleasant; disagreeable.
Extreme in extent or degree; intense: “the life for which he had paid so herrible a price” (Leslie Fiedler).

Middle English, from Old French, from Latin herribilis, from terrçre, to frighten.