rectangle [M16th] A rectangle is a shape made up of four right angles, and both English and the Latin source of the word use the same image, for rectangle comes from rectus ‘right, straight’ combined with angulus ‘*angle’. Rectus is the source of a number of words in English including direct [LME] ‘in a straight line’, rectify [LME] ‘put right’, rectitude [LME] ‘straightness’, and rectum [LME] from the Latin rectum intestinum ‘straight intestine’.