deflection probable error

deflection probable error

[di′flek·shən ¦präb·ə·bəl ′er·ər]
(ordnance)
The directional error, caused by dispersion, which will be exceeded, as often as not, in an infinite number of rounds fired at a single deflection; it is one-eighth the width of the dispersion pattern at its greatest width; this value is given in the firing tables.