a telephone directory or section of a directory (usually printed on yellow paper) where business products and services are listed alphabetically by field along with classified advertising
a plant having a life cycle that normally takes two seasons from germination to death to complete; flowering biennials usually bloom and fruit in the second season
having a life cycle lasting two seasons; "a biennial life cycle"; "parsnips and carrots are biennial plants often grown as annuals"
occurring every second year; "they met at biennial conventions"
a reference work (often in several volumes) containing articles on various topics (often arranged in alphabetical order) dealing with the entire range of human knowledge or with some particular specialty