Position error

The error in pitot-static instruments caused by the static ports not sensing true static air pressure. Position error changes with airspeed and is usually greatest at low airspeeds.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

Also defined in 1 more source

Error in the indication of the altimeter, ASI, and VSI caused by the air at the static system entrance not being absolutely still.

Pilot's Handbook of Aeronautical Knowledge, p. G-23