Deprecation
Deprecation is the discouragement of use of some feature, design or practice, typically because it has been superseded or is no longer considered safe, without (at least for the time being) removing it from the system of which it is a part or prohibiting its use.
Etymology
In general English usage, the infinitive "to deprecate" means "to express disapproval of (something)". It derives from the Latin verb deprecare, meaning "to ward off (a disaster) by prayer".
Thus, for one to state that a feature is deprecated is merely a recommendation against using it. It is still possible to produce a program or product without heeding the deprecation.
Software deprecation
While a deprecated software feature remains in the software, its use may raise warning messages recommending alternative practices; deprecated status may also indicate the feature will be removed in the future. Features are deprecated rather than immediately removed, to provide backward compatibility and give programmers time to bring affected code into compliance with the new standard.