From Longman Dictionary of Contemporary Englishslammerslam‧mer /ˈslæmə $ -ər/ noun → the slammer
Examples from the Corpus
slammer• Life in the slammer wasn't too bad for Bob Mitchum.• So heinous, in fact, that it carries a penalty of three months in the slammer.• Maxwell could spend some time in the slammer for failing to keep up with court-ordered guidelines after a marijuana conviction. 