Pen'ni·form adjective [ Latin penna feather + -form : confer French penniforme .] Having the form of a feather or plume. Found on http://www.encyclo.co.uk/webster/P/47
pennaceous, penniform Like a plume or feather. Pennaceous feathers have a central shaft (or rachis, 'main axis or shaft') with vanes branching off to either side. These vanes are also called 'barbs', that are connected to one another with barbules (pointed projections), or tiny strands that criss-cross to form a kind of mesh that holds all the ba... Found on http://www.wordinfo.info/words/index/info/view_unit/4251/