overpressure UK /ˌəʊ̯.vəˈpɹɛʃ.ə/US /ˌoʊ.vɚˈpɹɛʃ.ɚ/noun 1verb 1forms 3 noun1 •excess or markedly elevated pressure, especially a transient high pressure due to a shock wave... or whether the bronchiectatic cavity is due principally to a yielding of the bronchial walls to the inspiratory and expiratory pressure, to the overpressure of the engorging secretion, ... — 1904 verb1 •To subject to a high pressure formsoverpressured · overpressuring · overpressures