🐟 A fish's lower fin 🚀 A lower stabilizer

ventral fin

6.7

A fin under a plane or rocket that helps keep it stable in flight

noun
/ˈvɛntrəl fɪn/

Specialized

: aleta ventral

Engineers added two small ventral fins under the fuselage to reduce unwanted rolling during high-speed flight.

Examples

The model rocket gained improved yaw stability after attaching a ventral fin for flight tests.
During the test, the pilot felt the aircraft respond more smoothly with the new ventral fin installed.
The ventral fin helps stabilize the aircraft during flight.
Engineers designed the ventral fins to enhance control.
Engineers added two small ventral fins under the fuselage to enhance directional stability during flight.
The model rocket gained improved yaw stability after attaching a ventral fin for optimal performance in tests.
During the test flight, the pilot noticed that the new ventral fin significantly improved the aircraft's control.

Surface Forms

ventral fin singular

ventral fins plural

Morphology

ventral + fin

If a learner knows 'ventral' (pertaining to the front or lower part) and 'fin' (a projecting element), the meaning 'a fin mounted on the underside' is directly and transparently derived from combining the two. Although the term is technical (aeronautics/biology), its compositional structure is regular and cross-linguistically common, so a B1 learner who knows both constituents should be able to understand it.

Etymology

Ventral fin is also the name for a fin fixed under the body of a plane, rocket, or missile; picture a small wing on the underside that stops wobble and helps point the craft in the right direction. That's why engineers call it a fin that gives 'stability' and 'control'.