(Askeri) HAVAN YAN DÜZELTME LEVHASI: Rüzgar, sürüklenme vesaire için yapılacak düzeltmeleri ve bir havan istikamet açısına uygulanacak ayarlamayı bulmak için faydalanılan kontrol aleti
a small square board with a handle on the underside, used by bricklayers for holding mortar
A mortar board is a stiff black cap which has a flat square top with a bunch of threads attached to it. In Britain, mortar boards are sometimes worn on formal occasions by university students and teachers. In the United States, mortar boards are worn by students at graduation ceremonies at high schools, colleges, and universities