Delay
A suspension (SUS) (usually called delay in jazz) occurs when the harmony shifts from one chord to another, but one or more notes of the first chord (the "Preparation") are either temporarily held over into or are played again against the second chord (against which they are nonchord tones called the "Suspension") before resolving to a chord tone stepwise (the "Resolution"). Note that the whole process is called a suspension as well as the specific non-chord tone(s):
Suspensions may be further described using the number of the interval forming the suspension and its resolution; e.g. 4-3 suspension, 7-6 suspension, or 9-8 suspension. Suspensions resolve downwards; otherwise it is a retardation. A suspension must be prepared with the same note (in the same voice) using a chord tone in the preceding chord; otherwise it is an appoggiatura.
Decorated suspensions are common and consist of portamentos or double eighth notes, the second being a lower neighbor tone.
A suspended chord is an added tone chord with a "suspended" fourth or second as an added tone which doesn't resolve.
A chain of suspensions constitutes the fourth species of counterpoint; an example may be found in the second movement of Arcangelo Corelli's "Christmas Concerto".