abrupt

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Unexpectedly sudden: an abrupt change in the weather.
2. adj. Surprisingly curt; brusque: an abrupt answer made in anger.
3. adj. Touching on one subject after another with sudden transitions: abrupt prose.
4. adj. Steeply inclined. See Synonyms at steep¹.
5. adj. Botany Terminating suddenly rather than gradually; truncate: an abrupt leaf.

Century Dictionary and Cyclopedia

1. Broken or appearing as if broken away or off; marked by or showing a sudden breach or change of continuity; wanting continuation or completion: as, the path or the discourse came to an abrupt termination; an abrupt turn in a road. Hence Steep; precipitous: as, an abrupt cliff; an abrupt descent.
2. Figuratively, sudden; without notice to prepare the mind for the event; unceremonious: as, an abrupt entrance or address.
3. Lacking in continuity; having sudden transitions from one subject to another: as, an abrupt style.
4. In botany, terminating suddenly: as, an abrupt point: sometimes used in the sense of truncate: as, an abrupt leaf.
5. n. An abrupt place; a precipice or chasm.
6. To break off; interrupt; disturb.

Wiktionary

1. adj. Extremely steep or craggy as if broken up; precipitous.
2. adj. Without notice to prepare the mind for the event; sudden; hasty; unceremonious.
3. adj. Curt in manner; rude; uncivil; impolite.
4. adj. Having sudden transitions from one subject or state to another; unconnected.
5. adj. Suddenly terminating, as if cut off; truncate.
6. v. To tear off or asunder.
7. v. To interrupt suddenly.
8. n. Something which is abrupt.
9. adj. Extremely steep or craggy as if broken up; precipitous.
10. adj. Without notice to prepare the mind for the event; sudden; hasty; unceremonious.
11. adj. Curt in manner; rude; uncivil; impolite.
12. adj. Having sudden transitions from one subject or state to another; unconnected.
13. adj. Suddenly terminating, as if cut off; truncate.
14. v. To tear off or asunder.
15. v. To interrupt suddenly.
16. n. Something which is abrupt.

GNU Webster's 1913

1. adj. Broken off; very steep, or craggy, as rocks, precipices, banks; precipitous; steep.
2. adj. Without notice to prepare the mind for the event; sudden; hasty; unceremonious.
3. adj. Having sudden transitions from one subject to another; unconnected.
4. adj. Suddenly terminating, as if cut off.
5. n. An abrupt place.
6. v. To tear off or asunder.

WordNet 3.0

1. adj. extremely steep
2. adj. surprisingly and unceremoniously brusque in manner
3. adj. marked by sudden changes in subject and sharp transitions
4. adj. exceedingly sudden and unexpected