1. Literally, to put some substance through a sieve or a similar tool in order to remove smaller particles or things. In this usage, a noun or pronoun is used between "sift" and "through." Be sure to sift the sugar through a sieve to get rid of any lumps before adding it to the mixture.
2. To conduct a careful examination of some substance or group in order to isolate or remove something. We're spending the weekend sifting through all the applicants to determine a short list we can bring in for interviews. Our telephone operators have to sift through a huge volume of calls determining which are pranks and which are legitimate. He's sifting through the sand trying to find his lost ring.
sift something through something
to make something pass through something such as a sieve. she sifted the powdered sugar through a strainer. Please sift the soil through this screen and watch for bits of pottery.
sift through something
to examine all parts of something. The fire inspector sifted through the rubble, looking for clues to the start of the fire. We sifted through all the papers in the old trunk, but we did not find what we were looking for.
To search through some container or collection: I sifted through the laundry pile to find a pair of socks.