What is defined as the pressure required to move air through a filter at a certain airflow?

The concept described in the question refers to the pressure required to move air through a filter at a certain airflow, which is commonly known as initial resistance. This term is used to quantify the amount of pressure drop across a filter when it is new and clean, reflecting how much effort is needed to push air through the filter media at specified conditions.

On the other hand, other terms, while related, do not precisely capture the definition stated in the question. Airflow resistance relates broadly to all resistance encountered when moving air through any component, static pressure refers to pressure in a system at rest and not the dynamic action of moving air, and dynamic resistance typically refers to changes in resistance due to variables like airflow rate or changes in the filter condition over time. Therefore, initial resistance is the appropriate term that directly correlates to the pressure necessary to maintain a defined airflow through a clean filter.