An obelisk, less often spelled obelisque, is a tapered, four-sided stone monument that is usually monolithic and has a pyramidal top. Originally constructed by Ancient Egyptians and called tekhenu, the Greeks used the Greek term obeliskos to describe them, and this word passed into Latin and ultimately English. Though William Thomas used the term correctly in his Historie of Italie of 1549, by the late sixteenth century, Shakespeare failed to distinguish between pyramids and obelisks in his plays and sonnets. Ancient obelisks are monolithic and consist of a single stone; most modern obelisks are made of several stones.