Noun

• S: (n) plug-in, add-on (a software module that extends or enhances the capabilities of an existing application)
• S: (n) addition, add-on, improver (a component that is added to something to improve it) "the addition of a bathroom was a major improvement"; "the addition of cinnamon improved the flavor"
• S: (n) accessory, appurtenance, supplement, add-on (a supplementary component that improves capability)
• direct hyponym / full hyponym
• direct hypernym / inherited hypernym / sister term
• derivationally related form
• W: (adj) accessory [Related to: accessory] (furnishing added support) "an ancillary pump"; "an adjuvant discipline to forms of mysticism"; "The mind and emotions are auxiliary to each other"
• W: (adj) accessorial [Related to: accessory] (nonessential but helpful) "accessorial services included sorting and packing"
• W: (adj) appurtenant [Related to: appurtenance] (furnishing added support) "an ancillary pump"; "an adjuvant discipline to forms of mysticism"; "The mind and emotions are auxiliary to each other"
• W: (v) appertain [Related to: appurtenance] (be a part or attribute of)
• W: (adj) supplementary [Related to: supplement] (functioning in a supporting capacity) "the main library and its auxiliary branches"
• W: (adj) supplemental [Related to: supplement] (functioning in a supporting capacity) "the main library and its auxiliary branches"
• W: (v) supplement [Related to: supplement] (add as a supplement to what seems insufficient) "supplement your diet"
• W: (v) add on [Related to: add-on] (add to the very end) "He appended a glossary to his novel where he used an invented language"