A word used by Jacques Derrida as part of his critique of phonocentrism and the metaphysics of presence.
It is a playful word because it plays with two meanings of differ (to differ and to defer).
In addition, the word itself shows the dependence of speech on language, because for the French speaker there is no difference between difference and differance.
In other words, the difference is perceptible to the eye, but not to the ear.