Definition

Relating to a speed that is slower than the speed of sound in a specific medium, such as air.

Example

The aircraft was designed to operate at subsonic speeds for better fuel efficiency.

Conversation

Did you know that some planes can fly at subsonic speeds?

Yeah, that's pretty interesting! I always thought they had to be faster than sound.

It’s amazing how subsonic flight can still be so efficient.

Definitely! It must be great for fuel savings.

Synonyms & Antonyms

Root Explanation

Subsonic → It is formed from "sub-" (meaning under or below) and "sonic" (from Latin "sonus", meaning sound). The word "subsonic" refers to speeds that are below the speed of sound.

Memory Tip

Think of something that travels 'under' ('sub-') the speed of 'sound' ('sonic') — that's what subsonic means.

Visually Confused Words