The Collaborative International Dictionary
Napiform
Napiform \Na"pi*form\, a. [L. napus turnip + -form: cf. F. napiforme. Cf. Navew.] (Bot.) Turnip-shaped; large and round in the upper part, and very slender below.
Wiktionary
napiform
a. (context botany English) Shaped like a turnip; spherical at the top, but with a tapering bottom.