An Abscission

1. The act or process of cutting off.
2. (obsolete) The state of being cut off. [Attested only in the mid 17th century.]
3. (rhetoric) A figure of speech employed when a speaker having begun to say a thing stops abruptly
4. (botany) The natural separation of a part at a predetermined location, such as a leaf at the base of the petiole. [First attested in the late 19th century.]

Not to be confused with abscision, which only is defined as the first sense.