preposition
1 on the subject of; concerning : I was thinking about you | I asked him about his beliefs.
• so as to affect : there’s nothing we can do about it.
• ( be about) be involved or to do with; have the intention of : it’s all about having fun.
2 used to indicate movement within a particular area : she looked about the room.
3 used to express location in a particular place : rugs strewn about the hall | he produced a knife from somewhere about his person.
• used to describe a quality apparent in a person : there was a look about her that said everything.
adverb
1 used to indicate movement in an area : men were floundering about | finding my way about.
2 used to express location in a particular place : there was a lot of flu about | a thief about in the hotel.
3 (used with a number or quantity) approximately : reduced by about 5 percent | he’s about 35.
PHRASES
about to do something intending to do something or close to doing something very soon : the ceremony was about to begin.
be not about to do something be unwilling to do something : he is not about to step down after so long.
how about see how .
just about see just .
know what one is about informal be aware of the implications of one’s actions or of a situation, and of how best to deal with them.
up and about see up .
what about see what .

ORIGIN

Old English onb?tan, from on + b?tan [outside of.]