common fennel com·mon·fen·nel uncommon noun 1. strongly aromatic with a smell of aniseed; leaves and seeds used for seasoning Synonymscommon fennelFoeniculum vulgare 2. leaves used for seasoning Synonymsfennelcommon fennel Related words Broader terms herbfennel Parts common fennel Part of fennelfennel seed WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.