as days pass by

There are two very similar words, deprecate and depreciate. They are not the same word.
Deprecation is what has happened to a bit of an API that you’re not supposed to use any more. It means, in the technical community, that something is old or broken or has been replaced by a better alternative but still exists for backward coding compatibility, and you should think about not using it because it might go away in the future. (There’s also self-deprecating humour, to take an example of the different meaning of the word, but that’s not what we’re here to talk about.)
Depreciation is what happens to cars and houses and things when they go down in price after you’ve bought them. Economists no doubt have a technical meaning for it, but think of it this way: remember when you bought that beautiful new PowerBook or Mac G5 for about two grand, and ten seconds after you bought it it was worth seventeen hundred quid, and now you couldn’t sell it for mor than about fourteen hundred? That’s depreciation; an item’s price dropping over time just because it’s getting older.
Bits of specs or APIs or programs do not depreciate, in general. The easy way to remember this is as follows:
If you are talking about code, you almost certainly mean to say deprecate or deprecated. If you are talking about prices, you almost certainly mean to say depreciate or depreciation or depreciated.
People getting this wrong annoys me out of all proportion to the (frankly pretty tiny) magnitude of their error.