Loath, without the E, is an adjective meaning reluctant — I am loath to interrupt. Loathe, with the E, is a verb meaning to hate intensely. The E marks the verb, which is a useful pattern because the same holds for breath/breathe and cloth/clothe.
The core difference
An adjective and a verb, distinguished by a final E.
- loath (adjective) — reluctant: loath to admit it.
- loathe (verb) — hate: I loathe waiting.
The pattern
English marks several noun-or-adjective/verb pairs with a final E, and the vowel usually changes too: breath/breathe, cloth/clothe, bath/bathe. Loath/loathe belongs to the set, which makes it easier to remember than an isolated rule.
A note on spelling
Loth is an accepted variant of the adjective and appears in older British writing. It is now rare enough that it will read as a typo.
Frequently asked questions
Which spelling means to hate?
Loathe, with the E. Loath without it means reluctant.
Is "loathe to admit" wrong?
Yes — it should be loath to admit, because you need the adjective there rather than the verb.
What other words follow this pattern?
Breath and breathe, cloth and clothe, bath and bathe — the final E marks the verb.