So I went into the master bedroom closet and found an AC adapter plugged into an outlet. What's odd is there is nothing attached to the adapter and the adapter is not only plugged into the outlet but it is screwed on.

I thought about unplugging it but decided not to mess with it. Would anyone know what this thing is for?

I will post a picture of it when I get home.

I can't tell you my first thought, but then I'm a sick bastage.

Is this your house? Did someone break in and leave an adapter in your closet?

Could be a cable signal booster or part of an alarm system. 

So I'm a little confused by your description.  Are you saying the wire that leads out of the adapter isn't plugged into anything?  If that's the case, then unplugging it wouldn't matter now would it?

I can't tell you my first thought, but then I'm a sick bastage.

Twisted minds think alike...

It's power for your security alarm.

              T

Is this your house? Did someone break in and leave an adapter in your closet?

Yes, this is my home.  We've been here for over 7 years and just never noticed it.   

It's power for your security alarm.

T

If that is it, that seems like one seriously half assed way to put power into an alarm...

I think it's a hidden camera and someone put it there to spy on you.

LOL, 7 years in the house and you just now noticed it.  I wonder what else could be hidden in there.  Have you ever been in your attic? You might have a family of dwarfs living in there ;D

I believe it's a dc transformer that powers the keypad. Do you have a home security system?

But it doesn't make any sense to have the adapter plugged in an outlet that doesn't connect to anything. And, yes, we do have an alarm system.

Where is your nearest smoke alarm in relation to that plug?

Perhaps a 110 source of power to that kind of unit as many new alarms have both sources of power.  If the alarm was put in after the house was built, it would need to tie into the existing electrical system.

My guess would be for the alarm. The only reason it's screwed in is to be sure the pack doesn't fall out and interrupt a critical service.  I have a similar looking thing in my basement for the alarm.