Many technical terms appear in specifications, publications and application notes.
Some are easy to understand, others less so. The following glossary is intended to help with a basic understanding of what is meant where these terms are used. It is offered for guidance only and not as a definitive explanation. It is seldom uniform and in a duct there will normally be higher velocities near the centre and much lower velocities near the walls. Plotting the velocities measured across a duct will produce a velocity profile.