Recurring in scattered and irregular or unpredictable instances.

A city subjected to sporadic bombing raids.
sporadic

(of quantities) imprecise but fairly close to correct.

Lasted approximately an hour.
In just about a minute.
He's about 30 years old.
I've had about all I can stand.
We meet about once a month.
Some forty people came.
Weighs around a hundred pounds.
Roughly $3,000.
Holds 3 gallons, more or less.
20 or so people were at the party.
about, approximately, around, close to, just about, more or less, or so, roughly, some