N-COUNT [oft NOUN n](尤指计算机的)附加装置,外挂,插件 An add-on is an extra piece of equipment, especially computer equipment, that can be added to a larger one which you already own in order to improve its performance or its usefulness. (尤指计算机的)附加装置,外挂,插件
Speakers are sold as add-ons for personal stereos. [+ for]
扬声器作为随身听的附加装置出售。
Nintendo hopes to price the add-on modem at less than $200.