As a child I remember hearing the word Demic is used to describe something broken or unfit for purpose. It may be a slang term or particular to Lancashire, UK. Can anyone tell me where the word comes from comes from?
'Demmick' is recorded as second world war British army slang for on the sick list/out of commission; it's also listed by theurbandictionary.com as slang for an idiot or moron. I can't find any info on the derivation, but both of those usages seem to relate to the one you're familiar with.