Duodenary is an adjective that refers to a group of 12. Some synonyms for this word include dodecuple, dozenal, and twelfth-part. Other options might include words such as dozen, twelve-fold, and bicentenary (since a bicentenary can also refer to the 12th such anniversary). There are a range of terms that can be used to express the idea of a group of twelve, each with slightly different connotations or contexts in which they might be more appropriate. Depending on the specific situation in which the term is being used, different synonyms might be more or less appropriate.