Fall out of fashion, 9 letters
The state of falling into disuse, 12 letters
Falling into disuse or becoming out of date, 12 letters
The process of becoming obsolete, 12 letters
Like avaunt and prithee, 8 letters
Like a 386 computer, 8 letters
Like a Commodore 64, 8 letters
The property of being out of date and not current, 12 letters