1
general::
outside
not inside a building, but usually close to it:
• Whey don’t you go outside and play? • He was standing outside, smoking a cigarette.
out
outside – used mainly before the following prepositions or adverbs:
• We slept out under the stars. • Don’t stand out in the rain – come inside. • I can hear somebody out there .
outdoors/out of doors
away from buildings and in the open air – used especially when talking about pleasant or healthy things you do outside:
• In the summer, we like to eat outdoors. • Kids should spend as much time out of doors as possible.
in the open air
outside where the air is fresh:
• It’s good to exercise in the open air. • Leave the wood to dry slowly in the open air.
al fresco
outside – used when talking about eating outside:
• We prefer to dine al fresco.
Longman-Thesaurus