endangered UK /ɪnˈdeɪn.d͡ʒəd/US /ɪnˈdeɪn.d͡ʒɚd/ adjective1 •in danger, at risk, said of something where there is a strong possibility something bad will happen to it (for example, a species in danger of going extinct)I have but done my devoir, lady, as a good knight, in defence of an endangered maiden […] — 1825 formsmore endangered · most endangered