Outsideis an adverb, an adjective, a preposition or a noun.
We useoutsideas an adverb or an adjective to mean ‘not in a building’:
It was sunnyoutside, but not very warm.(adverb)
It’s a bit dark at night. We could put anoutsidelight there.(adjective)
Outsidecan also mean ‘external’, not part of an existing plan or situation:
They’re calling onoutsideinvestors for more support.
We useoutsideoroutside ofas a preposition to mean ‘not in a particular place, but near it’:
There’s a chair justoutsidethe room opposite.
She works in a software development company justoutside ofDublin.
As a preposition, we also useoutsideoroutside ofto mean ‘anywhere else apart from a particular place’:
There is a weight limit of 750g for lettersoutsideEurope.
Outside ofcan also be used with time expressions to mean ‘excluding’ or ‘apart from’:
Outside ofthe summer months, the hotel rates are lower.
Outsideas a noun is used to refer to the exterior of something. It is more informal thanexterior:
Theoutsideof the house is not very attractive, but inside it is beautiful.(or, more formal,The exterior of the house …)