ˈfȯrmənˌkrīs noun
( plural formenkrei·se -īzə ; or formenkreis·es -īsə̇z)
Etymology: German, literally, cycle of forms, from formen, plural of form (from Middle High German forme, from Latin forma ) + kreis circle, cycle — more at form , artenkreis
: a polytypic species (as of birds)