(transitive) To tag with keywords, as for example to facilitate searching.
2008, March 12, Philip Gefter, Type in ‘Native American’ and Search (Someday) 13 Million Photos, Besides being able to search the photography collections, of which 3,000 images have been scanned in so far, the feature is meant to provide a more subjective and spontaneous way for visitors to view the art: browsing images, looking at them sequentially and keywording, or tagging, them for themselves and other viewers.