Shakespeare and Milton were both remarkably inventive in their use of the English language, coming up with all kinds of new words, many of which are still in use to this day. Shakespeare was the first recorded writer to use the common word "addiction" (in Othello). And in act 3, scene 3, in Troilus and Cressida we have the word "fashionable," which is anything but as it's been commonly used ever since. Shakespeare was also renowned for adding the prefix "un-" to adjectives to create new words such as "uncomfortable," which we find in act 4, scene 5, of Romeo and Juliet.

Milton didn't create as many new words as Shakespeare, but in Paradise Lost he was the first to use "space" to refer to what we would also call "outer space." He also called the capital of Hell Pandaemonium, which literally means "all demons," but which nowadays tends to mean absolute chaos. Like Shakespeare, Milton created new words by adding the "un-" prefix to adjectives, such as "unoriginal," which ironically is completely original to Milton.