What is the definition or description of: lack of pleasure?

Anhedonia: Anhedonia, or lack of sense of pleasure often refers to the absence of getting joy or satisfaction out of things or activities most people enjoy. People sometimes describe this as the "blah's". It is commonly associated with depression and can be one of the later symptoms to respond to medication or psychotherapy, but can also be associated with neurological or schizophrenic syndromes.