The cold, lonely feeling on one's upper lip following the shaving of one's epic moveber mustache. This phenomenon occurs on December 1st, and can last for weeks. There is no known cure.
Bro 1: Ah man, I'm totally missing having a movember stache, I've got a serious case of Post MustacheDepression.
Bro 2: Whatever man, you had a pedostache anyways
That period of time, usually following New Year's, when you must take down all Christmas decorations and as a result, your house feels cold and naked.
John: Aw man... that spot by the fireplace where the Christmas tree used to stand feels so empty now.
Bob: Yeah, you're suffering from Post-Christmasdepression. We all get it.
When something that you have put a lot of time into recently is finally over (like the finale to a tv series that you love, or the end of a great video game trilogy) you are sometimes left melancholy, and with a feeling of "what do I do now". This lingering sadness is called "Post Completion Depression", though it's often shortened to P.C.D.
Anime enthusiast: So have you finished watching Kill la Kill yet!?
Casual anime fan: Yeah, it was great, in fact, I think I'm starting to get Post Completion Depression.
The all consuming pain that takes over your life when you return home after traveling for a long period of time. The feeling that something is missing or something is wrong. It is a devastating, depressing fase in your life, that will very likely be one of the hardest things you have to go through.
The feeling of not belonging and always missing little pieces of your heart is something you have to learn to live with.
P1 "my life doesn't make any sense, I don't feel comfortable in my own home"
P2 "wow, that sounds horrible"
P1 "yeah, I'm having a post-traveling depression"