Tychonoff space (or completely regular Hausdorff space, completely T3 space, T3.5 space) is a completely regular T0 space. (A completely regular space is Hausdorff if and only if it is T0, so the terminology is consistent.) Every Tychonoff space is regular Hausdorff.

Tychonoff space (or completely regular Hausdorff space, completely T space, space) is a completely regular T space. (A completely regular space is Hausdorff if and only if it is T, so the terminology is consistent.) Tychonoff spaces are always regular Hausdorff.