These words all pertain to what is extremely ugly, deformed or shocking, or to anything that deserves to be hated or causes aversion or nausea. Repulsive can refer to visual appearance that is hideous or to behaviour that is worthy of condemnation because of its crudity or immorality: a repulsive painting; such repulsive habits as belching and picking his nose. Repellent can refer literally to the warding off of something: an insect-repellent spray. But otherwise it is an intensification of the possibilities for repulsive : the repellent cruelty with which he treated his dog. Both words strongly imply a shocked or outraged reaction to the thing described, even to suggesting a physical drawing away from the object or a desire to drive it away: No matter how she tried to conquer her distaste, she found his disfigured body too repulsive to touch; using his cane in an attempt to smash the art object that he found so repellent.

Abhorrent derives ultimately from a Latin expression that refers to a horrified bristling, shuddering or shivering action. A comparable distaste, almost physical in its intensity, may well be indicated by the word, although now it applies less to visual appearance than to something that affronts one’s sensibilities or moral sense: the abhorrent policy of apartheid. In the context of moral indignation, abhorrent is the most forceful word here. Loathsome is closely related to such a use of abhorrent , but, whereas the latter might apply best as a sweeping condemnation of group action or behaviour, loathsome applies equally well to single acts or individuals: his loathsome mistreatment of his wife. In reference to group action, loathsome is less emphatic because the word may more clearly imply a personal aversion or disapproval that is not necessarily shared by others: loathsome customs that the newcomer found impossible to accept.

Disgusting and revolting are more like the first pair in suggesting a shocked or outraged reaction that can sometimes find physical expression. Disgusting can suggest an actual queasiness stimulated by something objectionable, whereas revolting can imply physical nausea or a psyche that reacts in rebellious upheaval to such a phenomenon: He found her cooking habits to be unhygienic and disguising ; impossible to be polite when confronted with his revolting impertinence. Both words lose any suggestion of these intense reactions when applied more generally, especially when used as loose hyperboles for irritation or annoyance: disgusting incompetence. Revolting , in fact, can give a tone of extreme informality when used in this way: a revolting development.

Repugnant also emphasizes a reaction of distaste or aversion, but is more formal than the previous pair. Also, because the word is less often used in loose exaggeration, it is considerably more forceful in effect: repugnant conditions in the restaurant kitchen that led to the proprietor’s being heavily fined; a repugnant indifference to human suffering. It is less forceful than abhorrent; to speak of repugnant , rather than abhorrent , crimes against humanity would show a want of feeling, since abhorrent expresses not only distaste but moral outrage as well.

Abominable is closer in tone to abhorrent and loathsome in stressing that something merits severe condemnation and hatred: abominable working conditions. This word has suffered from over-use and exaggeration to a greater degree than these other words, applying to anything that is relatively unpleasant: an abominable weekend of rain. Also, the word has been popularized as part of the phrase, "abominable snowman," referring to a legendary or imaginary man-beast reputed to exist in the mountains of Tibet; widespread humorous references to and extensions of this phrase have nearly incapacitated abominable itself for any serious use.