These words all mean within some degree of exactness or closeness, as in distance, time, amount, etc. approximately implies accuracy so near to a standard that the difference is not significant.

• It was approximately 100?in the shade; is approximately 3.1415.

About is often used interchangeably with approximately , but it does not stress the closeness to accuracy that approximately does: a hat costing about five dollars; reaching home at about dinnertime. Around sometimes appears in informal contexts in place of approximately or about : to go to bed around midnight; to invite around fifteen people to a picnic.

Roughly is often used in place of approximately or about when there is no real attempt to be exact.

• The cost of the car repairs was estimated at roughly fifty dollars; The population of London is roughly 8,000,000.

Roughly also carries a suggestion of casualness or haste, which the other words do not convey.

• The books were shelved roughly in alphabetical order; Roughly speaking, I would guess that we are headed for a depression.