Post Convention Depression that is always, always suffered after an amazing BBYO convention full of friends, spooey, Alephs, BBGs, leadership, dancing, and admiring the amazing regional board.

Pitch Circle Diameter.

Refers to the number of lug nuts in a wheel and the distance from one lug to the opposite end of the lug arrangement. This is also known as the bolt pattern.

Typically expressed in (Number of Lugs) X (Distance), for example, 5x4.50 (in inches) or 5x114.3 (in metric).

Acronym for 'PussyCat Dolls', a girl musical group. See pussycat dolls.

PCD stands for programmed cell death. This happens when a cell is in a state of poor health/disrepair, so release of special proteins (like cytochrome c - found in mitochondria) either from inside of the cell or by another cell, triggers an organized chain reaction of events, resulting in the degradation and destruction of proteins and nucleic acids inside the cell.
The genes responsible for the proteins that signal PCD are not working correctly in cancer cells.

Proper Creep Distance. Adj/verb. The appropriate distance at which you should walk behind an attractive chick. You should maintain this in order to get a good view but avoid alerting her to how hard you're staring at her fine ass and/or legs and making her run off like a spooked gazelle.

Post Concert Depression
When you go to a lit concert and have fun, then you wake up the next morning feeling sad and missing it, while looking through all of the pictures and videos you took. This could last for a longer time

CD-R with porn video/pic files burned onto them. Usually found in groups.