add-on

n.附加物; 附加装置 复数：add-ons 牛津词典 noun 附加物；附加装置a thing that is added to sth elseThe company offers scuba-ping as an add-on to the basic holiday price.这家公司提供带水肺潜水活动，不包括在基本度假费用以内。 add-on software (= added to...