Hydrodynamic

Tuna have a hydrodynamic body.

The whale is an immense marine mammal, with a hydrodynamic, hairless body, a horizontal fin on its tail and a hole on the top of its head for breathing.

On the descent from Semmering to Payerbach-Reichenau, with a ruling gradient of 1 in 39 [...], the Voith hydrodynamic brake kept the train within the 19 and 23 m.p.h. limitations without recourse to air brakes, [...].