"Bagel feature" is an informal term used to describe software or technology features that are not essential but are added to make a product more attractive. Some synonyms for this term include "frill," "ornamentation," "embellishment," "add-on," and "extra." Other more specific synonyms could include "bells and whistles," which describes features that are flashy but not necessarily functional. Another term that can be used is "luxury feature," which is used to describe features that are not necessary for the basic function of a product but add to the user experience. Overall, these synonyms are useful ways to describe non-essential features that enhance a product's appeal.