Defect

As a noun, a defect is a fault, flaw, or problem that makes something less perfect. As a verb, to defect is to leave one side, group, or country to join another.

Both uses come from Latin “defectus,” meaning “failure, lack,” from “deficere,” “to fail, run short, desert,” from “de-” (down, away) and “facere” (to do, make). The noun focuses on something missing; the verb on someone abandoning.