Definition of INFLORESCENCE. 1. a: the mode of development and arrangement of flowers on an axis b: a floral axis with its appendages; also: a flower cluster. 2.: the budding and unfolding of blossoms: flowering.See inflorescence defined for kids. ADVERTISEMENT.. a: the mode of development and arrangement of flowers on an axis b: a floral axis with its appendages; also: a flower cluster. 2. : the budding and unfolding of blossoms: flowering. See inflorescence defined for kids.