calamondin
noun(cal-a-mon-din)
a small hybrid citrus tree (Citrofortunella microcarpa synonym Citrofortunella mitis synonym Citrus mitis) of warm regions cultivated chiefly as an ornamental; also : its small, tart, orange fruit resembling a mandarin or kumquat and yielding an acidic juice used especially as a flavoring agent or in beverages and marmalades