acidophilic UK /ˌæsɪdəʊˈfɪlɪk/US /ˌæsɪdoʊˈfɪlɪk/ adjective2 •Thriving under acidic conditions; relating to or being an acidophile. •Easily stained with acidic dyes, such as eosin. formsmore acidophilic · most acidophilic