al-Haytham n 1: an Egyptian polymath (born in Iraq) whose research in geometry and optics was influential into the 17th century; established experiments as the norm of proof in physics (died in 1040) [syn: {Alhazen}, {Alhacen}, {al-Haytham}, {Ibn al-Haytham}, {Al-Hasan ibn al-Haytham}]