Intense disgust fused with hatred.
Intense disgust fused with hatred — a settled, simmering aversion that shades into hate.
High-intensity disgust fused with hostility — the term that most clearly shades from disgust into active hate. More sustained, personal, and emotionally charged than the visceral disgust or the sudden revulsion: a settled animosity rather than a momentary turn of the stomach. You can loathe a person, a rival, or yourself (note self-loathing). Less morally framed than abhorrence (which condemns something as evil) but stronger in hostility.
A verbal noun from loathe (late 14c.), from Old English laðian, from lað “hated; hateful” (the root of loath). The literal Germanic sense is “hateful, loathsome.”
The noun has meant “abhorrence / hatred” consistently since the late 14c. A historical feature of the verb is the now-obsolete impersonal construction (“it loathes me” = “I am disgusted”), a grammatical rather than semantic change. No reliable recent-generation shift.