Roughness, Waviness, and Form

This picture shows roughness, waviness, and form '
Figure 1. Surface profile characteristics

Roughness: consists of the closely space irregularities. It is caused by cutting tool marks or the grit of a grinding wheel.

Waviness: consists of more widely spaced irregularities. It is produced by vibration or chatter in the machine.

Form: consists of long-period por non-cyclic deviations. It is produced by errors in ways or spindles, uneven wear.

Reference

T. V. Vorburger, J. Raja,  Surface Finish Metrology Tutorial, NISTIR 89­4088 (National Institute of Standards and Technology, Gaithersburg, MD, 1990)