transonic

[ tran-son-ik ]

adjective

, Chiefly Aeronautics.

1. close to the speed of propagation of sound; moving at 700–780 miles per hour (1127–1255 km/h) at sea level.

transonic

/ trænˈsɒnɪk /

adjective

1. of or relating to conditions when travelling at or near the speed of sound

transonic

/ trăn-sŏn′ĭk /

1. Relating to or capable of speeds at or near the speed of sound (at or approaching Mach 1) or to aerodynamic conditions for bodies travelling at such speeds.
2. Compare hypersonic

Word History and Origins

Origin of transonic¹

First recorded in 1940–45; trans- + sonic

Example Sentences

They carry exotic names—such as transonic truss-braced wings, blended-wing bodies and double bubbles—that reflect how far removed they are from most of the conventional planes that now carry commercial passengers worldwide.

From Singularity Hub 

The solution was the X-1 transonic research aircraft that Yeager piloted.

From Popular-Science