The word "hideous" describes something that is extremely ugly or unpleasant to look at. It can also refer to something that is morally offensive or shocking. When you think of something hideous, you might imagine an object, a creature, or even an action that elicits a strong sense of disgust or revulsion.
The word "hideous" comes from the Middle English "hideus," which is derived from the Old French "idueux," meaning "hateful, detestable," and traces back to the Latin "hideosus," meaning "terrible, frightful." The root "hio" means to be afraid or to shrink back, which reflects the negativity associated with the word.