The pushrod is the part of a caulk gun that connects the plunger head to the trigger; also is used to open the plunger fully for easy loading

PVC is a white plastic pipe used for supply lines and also drain, waste and vent pipes. 

PVC cement is a chemical solvent-based glue used to weld PVC pipe and fittings together

PVC primer is a solvent-basedchemical used to clean and soften plastic pipe and fittings before the glue is applied. Typically purple in color