1.
You use ~ to indicate that there is very little of something or not as much of something as there should be.
She began to berate the police for paying ~ attention to the theft from her car.
ADJ: usu ADJ n
2.
If you describe an amount as ~, you are emphasizing that it is small.
This hole was a ~ .23 inches in diameter...
= mere
ADJ: a ADJ amount emphasis