1. Tapering at both ends; spindle-shaped. (Google Dictionary)
2. Shaped like a spindle with yarn spinned on it; having round or roundish cross-section and tapering at each end. (wiktionary.org)
3. Spindle-shaped, that is being wide in the middle while narrowing or tapering at both ends. (biology-online.org)
4. A body shape common to many aquatic animals, characterized by being tapered at both the head and the tail. (wikipedia.org)
Syn: spindle-shaped, cigar-shaped
Word origin: From Latin fusus (“spindle”) + –iform.