ˌwriter’s ˈcramp noun [uncountable] a feeling of stiffness in your hand that you get after writing for a long time
[TahlilGaran] Dictionary of Contemporary English ▲
writer's cramp n. Pain in the fingers or hand caused by too much writing.
Holding your pencil too tightly for too long often gives you writer's cramp. Often used humorously to stress the idea that you have been doing a lot of writing.
By the time Mary finished her Christmas cards she complained of writer's cramp. [TahlilGaran] English Idioms Dictionary ▲