This technical term provides a good example of the mis-named, the loosely-defined, the nameless and the only-belatedly-named in Middle English poetics. It’s a word sometimes flung about by my students when close-reading: any syntactical break (i.e. anywhere a line of poetry has a division between grammatical phrases or clauses, and especially if it’s near the middle of the line) gets called a caesura without too much thought. It’s one of those technical terms that gives you faux expertise: you can spot something easy (i.e. a syntactic break) and label it with a word which makes it seem as if you are analysing the metre. Joseph A Dane is usefully strict about how relevant the word is for Chaucer’s metre in this article (the answer is not very!).