For example, the noun flounder can refer to several kinds of flatfish . The third grouping relation is called twins. These are synsets that have at least three words in common. For example, one sense of duo is a musical group and another is a musical composition. Both synsets contain duet , duette , and duo .
Transitivity is used to combine groups of overlapping senses into the largest sense groups possible.
Some similar senses of verbs have been grouped by the lexicographers. As with the noun senses, transitivity is used to combine groups of overlapping senses into the largest sense groups possible. There are, of course, exceptions to all of the relations. Candidates for cousin and twin groupings are checked by hand and those that should not be grouped together are listed in the exception list file. Coverage of verb groups is incomplete.