Like HorizontalStripes but this metaphor makes more sense for those of us who visualise our applications as a series of layers from the UI down to a database layer. This way when we talk about an end to end slice we mean a piece of the application that utilises the UI to manipulate the domain layer which results in different data being stored in the persistence layer.

It depends on whether you are looking at a top-to-bottom stack of layers (in which case VerticalSlices), or a left-to-right sequence diagram (in which case HorizontalStripes). Works from either angle.