pustule

(pŭsˈcho͞ol, pŭsˈtyo͞ol)

1. A small inflamed elevation of the skin that is filled with pus; a pimple.
2. A small swelling similar to a blister or pimple.
3. Something likened to an inflamed, pus-filled lesion: “a cool glimpse of green between hot pustules of sooty sprawl” (Nicholas Proffitt).