pro·te·a·some 
(prōtē-ə-sōm′)
(prōtē-ə-sōm′)n.
A cellular protein complex consisting of proteolytic enzymes that degrade endogenous proteins, especially those that are damaged, pathogenic, or no longer of use.
[Alteration of earlier prosome (influenced by PROTEASE) : PRO(GRAMMED), from the earlier belief that proteasomes played a role in regulating messenger RNA translation + -SOME.]