-itis

The story

1. Ancient Greek · derived from-ῖτις“pertaining to”
2. New Latin · derived from-itis
3. English today-itis

From New Latin -itis, from Ancient Greek -ῖτις (-îtis, “pertaining to”). This is the feminine form of adjectival suffix -ῑ́της (-ī́tēs). The English suffix derives from the feminine form due to its use with the feminine noun νόσος (nósos, “disease”), particularly with ἀρθρῖτις (νόσος) (arthrîtis (nósos), “disease of the joints”) (one of the earliest English borrowings from which the suffix was extracted and abstracted). Adding "-itis" to the end of a word or phrase can give a humorous sense by generalization.