Pitch
Pitch turns up in 2 fields: fasteners, hydrography. Here is what it means to the people in each one.
Pitch in fasteners
The distance from one thread crest to the next, measured parallel to the screw axis.
The axial distance between corresponding points on adjacent threads. Metric threads state it directly in millimeters, such as the 1.25 in M8 x 1.25, while inch threads state its reciprocal as threads per inch. On a single-start fastener, pitch equals lead, the distance the nut advances in one turn; on multi-start threads the two are different.
"Pitch looks like one and a quarter, not one and a half, so that M10 is metric fine, don't run that nut on with the gun."
Pitch in hydrography
Bow-up or bow-down rotation of a vessel, which shifts sonar footprints forward or aft along the track.
Rotation about the athwartships axis, measured by the motion sensor and applied to place each ping along track. Pitch errors move soundings forward or aft by roughly depth times the angle error, so features appear in different places on reciprocal lines. Pitch bias is resolved in the patch test by running reciprocal lines at the same speed over a slope or a distinct feature.
"Pitch bias pushes the wreck 3 metres forward on every line, sort it before we start developing."