Merging taxonomy terms
Sometimes, especially if a taxonomy field is set up as freetagging, multiple spellings/misspellings/abbreviations are added to a vocabulary, which can cause confusion. Terms that refer to the same thing can be merged, however, through the Taxonomy Manager.
Be VERY CAREFUL with this tool because terms cannot be un-merged without doing a database restore from a backup. Do not merge biological taxonomy terms unless you are very sure of what you are doing.