A topological space $Y$ in which the given topological space $X$ is an everywhere-dense set. If $Y$ is a compact space, then it is called a compact extension, and if $Y$ is a Hausdorff space, it is called a Hausdorff extension.
Compact extensions are also called compactifications, cf. also Compactification.
[a1] | E. Čech, "Topological spaces" , Wiley (1966) |