Said of a program or feature that is considered obsolescent and in the process of being phased out, usually in favor of a specified replacement. Deprecated features can, unfortunately, linger on for many years. This term appears with distressing frequency in standards documents when the committees writing the documents realize that large amounts of extant (and presumably happily working) code depend on the feature(s) that have passed out of favor. See also dusty deck.
[Usage note: don't confuse this word with `depreciate', or the verb form `deprecate' with `depreciated`. They are different words; see any dictionary for discussion.]