Refers to a person who lives in a particular dwelling, often used in contexts like rental housing or when discussing who inhabits a place.
The tenants of this apartment are all young people.
We are looking for an occupant for the vacant house.
Compound of 住み (continuative form of 住む 'to live') and 手 ('person'). The exact historical derivation is uncertain, but the word follows a common pattern for agent nouns.