A rectangle is a four-sided shape with straight sides and four right angles, where opposite sides are equal in length.
From Latin *rectangulus* meaning ‘right-angled’, from *rectus* (straight, right) + *angulus* (angle). It came into English through French with the specific geometric meaning.
The ‘rect’ in rectangle is the same as in ‘correct’ and ‘rectify’—it means straight or right. So a rectangle is simply a ‘right-angled’ shape, which is why all its corners are perfect 90° angles.
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