Out-of-doors and Out

Out-of-doors noun - That part of the physical world that is removed from human habitation.

Out and out-of-doors are semantically related in outside topic. In some cases you can use "Out" instead the phrase "Out-of-doors" as an adverb or an adjective, when it comes to topics like place, outdoors.

Out adjective - Fully committed to achieving a goal.

Out-of-doors and out are semantically related in place topic. You can use "Out-of-doors" instead the word "Out" as an adverb or an adjective, if it concerns topics such as outside, outdoors.