the mixture of gases that surrounds the earth and that we breathe:
air pollution; Let's go out for some fresh air; I need to put some air in my tyres; currents of warm air
SYNONYMS outside in the open air • outdoors • out of doors • in the fresh air • under the stars
These words all mean not inside a building.
outside not inside a building: Let's eat outside. in the open air (often approving) not inside a building, especially in a place where the air is clean and fresh, for example in the countryside or in a park. outdoors not inside a building: Try to avoid going outdoors in very cold or icy weather. out of doors outdoors: You should spend more time out of doors; It was the first time in his life that he'd slept out of doors.
OUTSIDE, OUTDOORS OR OUT OF DOORS? Outside is often more particular and outdoors is usually more general: Go and play outside (= out of this house now); Fewer and fewer children spend time playing outdoors (= out of their houses in general). Out of doors is used in the same way as outdoors, but it is less frequent, especially in North American English.
in the fresh air (approving) outside where the air is clean and fresh, especially when this makes you feel good. under the stars outside at night, especially on a fine, clear night: We often slept under the stars.
PATTERNS AND COLLOCATIOMS • to sleep/camp outside/in the open air/outdoors/out of doors/in the fresh air/under the stars • to eat/play/spend time outside/in the open air/ outdoors/out of doors/in the fresh air • to go/venture outside/outdoors/out of doors/out in the open air/in the fresh air