in modern prosody, a pause within a poetic line that breaks the regularity of the metrical pattern. It is represented in scansion by the sign ‖. The caesura sometimes is used to emphasize the formal metrical construction of a line, but it more often introduces the cadence of natural speech patterns and habits of phrasing into the metrical scheme. The caesura may coincide with conventional punctuation marks, as in the following Shakespearean line (Shakespeare, William), in which a strong pause is demanded after each comma for rhetorical expression:

The caesura is not necessarily set off by punctuation, however, as in this line from John Keats: (Keats, John)

In Germanic and Old English alliterative poetry, the caesura was a formal device dividing each line centrally into two half lines, as in this example from “The Battle of Maldon” (Battle of Maldon, The):

In formal, Romance, and Neoclassical verse, the caesura occurs most frequently in the middle of the line (medial caesura), but in modern verse its place is flexible; it may occur near the beginning of one line (an initial caesura) and near the end of the next (terminal caesura). There may be several caesuras within a single line or none at all. Thus, it has the effect of interposing the informal and irregular patterns of speech as a subtle counterpoint to the poem's regular rhythm; it prevents metrical monotony and emphasizes the meaning of lines.

Types of caesura that are differentiated in modern prosody are the masculine caesura, a caesura that follows a stressed or long syllable, and the feminine caesura, which follows an unstressed or short syllable. The feminine caesura is further divided into the epic caesura and the lyric caesura. An epic caesura is a feminine caesura that follows an extra unstressed syllable that has been inserted in accentual iambic metre. An epic caesura occurs in these lines from Shakespeare's Macbeth: “but how of Cawdor? / The Thane of Cawdor lives.” The lyric caesura is a feminine caesura that follows an unstressed syllable normally required by the metre. It can be seen in A.E. Houseman's “they cease not fighting / east and west.”

In classical prosody, caesura refers to a word ending within a metrical foot, in contrast to diaeresis, in which the word ending and the foot ending coincide. It is strictly a metrical element, not an element of expression.