The word "loathsome" is derived from the following word parts:
Loath: This part comes from the Old English word "lāð," meaning hostile or unpleasant.
-some: The suffix "-some" is added to "loath" to form an adjective causing or characterizing a specified quality or thing.
So, "loathsome" combines the root "loath" with the suffix "-some" to convey the meaning of something causing intense dislike or disgust.