From Longman Dictionary of Contemporary Englishpustulepus‧tule /ˈpʌstjuːl $ -tʃuːl/ noun [countable] medicalMI a small raised spot on your skin containing pus
Examples from the Corpus
pustule• The broken pustules then burned like dots of acid.• Avicenna claimed it caused melancholia, and Rhazes cautioned that it inflamed the blood and caused pustules in the mouth.• It was covered in weeping pustules and had been isolated from the group.Origin pustule (1300-1400) Latin pustula 