klendusity

The story

1. Ancient Greek · borrowed fromκλειδόω“I lock up”
2. English todayklendusity

From Ancient Greek κλειδόω (kleidóō, “I lock up”) (see κλείς) + ἔνδυσις (éndusis, “entry”) (see ἐνδύω) + -ity, because the route of entry for pathogens is supposed to be locked up. The word is a clumsy coinage; a more systematic approach would have involved cleido-.