1. A method for refining homonyms and synonyms in a plurality of tags, comprising: receiving, by a tag refinement system, a plurality of tagging actions each of which associates one or more of the plurality of tags with a digital object; and extracting, by the tag refinement system, a first subset of tags from the plurality of tags, wherein the first subset of tags have a higher collective relativity-similarity score comparing to a second subset of tags selected from the plurality of tags, and the first subset of tags, different from the second subset of tags, have a same predetermined tag count as the second subset of tags.