A line multiverse is a type of 4+1-dimensional multiverse in which each universe is adjacent to exactly two other universes, and they are arranged in a line.

Each universe acts as a point in the line. The line can be finite or infinite. If it is finite it will have a "first" and/or "last" universe. Otherwise it will allow for indefinite travel in one direction or both. The line can be straight or curved but it cannot loop back onto itself at any point which prevents it from having a constant positive curvature.

A similar type of multiverse that loops back eventually is a circle multiverse.