Definition:

To warp (verb) means to deform a shape. In pottery, warping is a fault in which the clay object deforms during drying or firing. It is generally due to uneven drying or heating, or overfiring. Warpage (noun) can be either almost imperceptible through to gross deformation.

Also Known As: deformation (usually, when used by a potter, this means a deliberate changing of a shape)

Examples:

The plates warped because the kiln went a cone over the target temperature.

(verb - past tense)

The warpage of the bowl is from uneven drying due to unevenly thrown walls. (noun)