1) Basketball statistic 2) Sit for a fake photo 3) To push 
[basketball] Poss is a stat used to estimate the number of offensive possessions a player is accountable for. It was developed by Dean Oliver, the first full-time statistical analyst in the NBA. http://basketball-reference.com/about/glossary.html ...
• (v. t.) To push; to dash; to throw.
Poss transitive verb [ See Push .] To push; to dash; to throw. [ Obsolete or Prov. Eng.] « A cat . . . possed them [ the rats] about.» Piers Plowman. 
Palomar Observatory Sky Survey
Old name for the thickening at the place of refinement. The grafting is called buffoonery, the scion is called possessive material and the performer is called posser.