Definition

In a way that is slower than the speed of sound.

Example

The aircraft flew subsonically, creating less noise than supersonic jets.

Conversation

Did you hear that jet fly by earlier?

Yeah, it was so loud! I wonder if it was flying subsonically.

I think that might be the case; it seemed to be moving really fast.

Exactly! It's fascinating how they can travel subsonically and still create such a noise.

Synonyms & Antonyms

Root Explanation

Subsonically → It is formed from "sub-" (meaning under or below) and "sonic" (from Latin "sonus", meaning sound) and the suffix "-ly" (meaning in a manner). The word "subsonically" refers to something that occurs at a speed below the speed of sound.

Memory Tip

Think of something happening 'under' ('sub-') the speed of 'sound' ('sonic') — that's why subsonically means at a speed below sound.

Visually Confused Words