Two houses joined together with a common wall or walls; they are usually registered under Torrens Title
One or two dwellings built side by side, separated by a common wall, which shares a common roof
A semi-detached house is a house that is joined to another house on one side by a shared wall. a semi-detached house in Highgate. Semi-detached is also a noun. It was an ordinary, post-war semi-detached. a semi-detached house is joined to another house on one side detached, terraced terraced