My friend was shocked to see "inmate" next to her g g auntie's name when she registered her mother's death on a Scottish death certificate. Her stepfather worked as an attendant at Aberdeen Lunatic Asylum and she put 2 and 2 together and thought the worst. Auntie had had an illegitimate son the previous year.
On Scottish death certificates from 1855 the informant gives a relationship eg son, whether present at the death and an address. If the son does not stay at the same address he gives his address. If however he does stay at the same address the archaic term "inmate" meaning living at the same address is used.
Here are three examples from the same certificate.