Source : Webster's Revised Unabridged Dictionary (1913)

Loathsome \Loath"some\, a.
   Fitted to cause loathing; exciting disgust; disgusting.

         The most loathsome and deadly forms of infection.
                                                  --Macaulay.
   -- {Loath"some*ly}. adv. -- {Loath"some*ness}, n.

Source : WordNet®

loathsome
     adj 1: causing or able to cause nausea; "a nauseating smell";
            "nauseous offal"; "a sickening stench" [syn: {nauseating},
             {nauseous}, {noisome}, {offensive}, {sickening}, {vile}]
     2: highly offensive; arousing aversion or disgust; "a
        disgusting smell"; "distasteful language"; "a loathsome
        disease"; "the idea of eating meat is repellent to me";
        "revolting food"; "a wicked stench" [syn: {disgusting}, {disgustful},
         {distasteful}, {foul}, {loathly}, {repellent}, {repellant},
         {repelling}, {revolting}, {skanky}, {wicked}, {yucky}]