1. Literally, to use a sieve or a similar tool or method to remove small things from a larger substance. A noun or pronoun can be used between "sift" and "out." Be sure to use a sieve to sift out any lumps from the sugar before you add it to the mixture. People used to sift flecks of gold out of the soil in this river back in the late 1800s.

2. To isolate and remove something from some larger thing or group after or with careful examination. A noun or pronoun can be used between "sift" and "out." We have a very rigorous vetting process to sift unsuitable candidates out of the application pool. Our telephone operators are under huge pressure on a daily basis to sift out prank calls from legitimate ones.