Trans-universal travel AKA Crossover with Science!

1 - line
2 - plane
3 - volume
4 - time
5 - alternative timelines (defined by a point of divergence)
6 - alternative universe (universal constants are the same)
7 - alternative universe (at least one universal constant is different)
8 - alternative universe (multiple universal constants are different)
9 - a sea of possibility
10 - everything and nothing

Multiverse is anything in the 8th-dimension and "below", which may contain 'smaller' multiverses. Side note, the " Displaced Multiverse" and "Renegade Displaced Multiverse" are 7th-dimensional structures with an 8th-dimensional connection.