pinhead I. \ˈ ̷ ̷ˌ ̷ ̷\noun 1. a.: the head of a pin b.: something very small or insignificant 2. a.: a microcephalic idiot b.: a very dull or stupid person : fool < seems an awful pinhead — Wolcott Gibbs > 3.: a part of a plow containing pinholes for a pin the position of which regulates the depth of furrow 4.: a small minnow II. \ˈ ̷ ̷| ̷ ̷\adjective : pinheaded < pinhead philosophy … and abysmal ignorance — James Kelly >