Also written as "parcan" and "PARcan". A luminaire using a PAR lamp as its light source. Can be made of steel (Altman P64), spun aluminum (James Thomas Engineering, Tomcat, many others), or plastic (Unipar).
May also apply to the ETC Source Four PAR, and Altman StarPar (and other copies), even though these fixtures don't use PAR lamps.
For the lighting historian:
From http://www.controlbooth.com/wiki/PAR :