"emotion, feeling, fit, frenzy, madness, lunacy"
Today this word means "intense delight" or "rapture" - a sense which was emerging in the 16th century, but long preceded by a much wider range of senses, and these are the ones found in Shakespeare. It expressed any point on a scale of emotional intensity: the "weak" end can be illustrated by the description of Venus, "Thus stands she in a trembling ecstasy" (Venus and Adonis 895), where it means little more than "emotion". In the middle we have the notion of "mental fit" or "frenzy", illustrated by the description of the confused and angry Antipholus: "Mark how he trembles in his ecstasy" (Comedy of Errors IV.iv.49). At the "strong" end we have the various references to Hamlet by Ophelia and Gertrude, such as the latter's "This bodiless creation ecstasy Is very cunning in", to which Hamlet immediately replies "Ecstasy?" and denies it, making the older sense perfectly clear: "It is not madness that I have uttered".
David Crystal is author, with Ben Crystal, of Shakespeare's Words, published by Penguin next month