

Yeah, adding in- as a prefix often does mean that, but it can also mean in, on, or into (among others) as a prefix or just part of the core word. And in this case inflammable comes from adding the suffix -able to inflame, a word that already starts with in- in it’s into meaning. And one definition of inflame is “to burst into flames.”

In college I didn’t hang out with my classmates much, I mostly hung out with townies. Obviously not all townies were dumb, but some were very dumb, nice though.