extending or operating in several directions at the same time; functioning or going in more than one direction: a multidirectional stereo speaker system.

What do you mean by multidirectional?

: able to move, function, or operate in more than one direction multidirectional forces Since they radiate sound toward both front and back, these speakers have an unusually open and airy sound (as do other multidirectional designs) that is musically very pleasing.—

Is multi Day One word?

In situations like this, there is often a legitimate choice between spellings. Dictionaries' research can give different results where it's about 50 - 50. For instance, OxfordDictionariesOnline gives only multi-day.