Earlier this week someone I was talking to insisted that it's acceptable to use "prior" interchangeably with "former" in the context of "former vs. latter," i.e. to mean the first item of two things listed.
For example, "I had to go to the store and pick up Jimmy from school, but I skipped the prior because the latter was more important." This didn't sound right to me, but the Oxford thesaurus lists "prior" as an antonym to the second definition of "latter," which is "denoting the second mentioned of two things." Thoughts?