Bleen

Bleen is an artificial predicate, coined from "green" and "blue" by philosopher Nelson Goodman[?] in one of the seminal works in the philosophy of science, Fact, Fiction, and Forecast. The predicate is used to illustrate what Goodman calls the new problem of induction[?].

Specifically, "bleen" means "blue before January 1, 2000 and green on or after January 1, 2000". See also grue.