extropy

First coined to serve as an antonym of entropy, substituting its en- element (representing the prepositional prefix ἐν (en), en, “in” in its Ancient Greek etymon ἐντροπία (entropía), entropia, “a turning towards”) with ex- (representing the Ancient Greek ἐξ (ex), ex, “out of”, “from”); because ἐξ (ex) takes the form ἐκ (ek) when prefixed to an element beginning with τ (t), the analogical spelling is ectropy (or, alternatively, ektropy), as if after the Ancient Greek *ἐκτροπία (ektropía, “a turning out of”).

来源：wiktionary