One that does not bring up any phlegm or mucus, and is also known as an unproductive cough.
A dry cough is a symptom of COVID-19 and can be described as “unsatisfying” because being unproductive, it does not help to clear the throat or lungs of any mucus or phlegm.
It has a very consistent sound and can seem hoarse or mimic barking. Listen to the sound of a dry cough on this clip: https://youtu.be/nbCbOis-mwo?t=102.
A wet or productive cough, although less common, can also be a symptom of COVID-19.