The Latin word antenna meant “sail yard,” which is the long spar that supports and spreads the sail on a sailing vessel. The Greek word for a sail yard was keraia, but that was only one meaning of this word. The primary meaning was “horn.” The philosopher Aristotle used keraiai to describe the feelers of insects, probably because of their resemblance to the horns of some larger animals. In a Latin translation of Aristotle’s work made during the Renaissance, the word antennae was used for Greek keraiai. In English we still use antennae for insects’ feelers. And now we also use antenna for the metal rods that pick up radio waves and seem to “feel the air” like the antennae of an insect.