Refers to the tip of a tube, hose, or firearm barrel. Can be used literally for a nozzle or muzzle, and figuratively for being at gunpoint.
I pointed the nozzle of the hose at the flower bed and watered it.
The criminal pointed the gun at the store clerk.
Compound of 筒 (tsutsu, 'tube, cylinder') and 先 (saki, 'tip, end'). The reading つつさき is a straightforward combination of the two components.