abrupt

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Unexpectedly sudden.
• adjective Surprisingly curt; brusque.
• adjective Touching on one subject after another with sudden transitions.
• adjective Steeply inclined. synonym: steep.
• adjective Botany Terminating suddenly rather than gradually; truncate.

from The Century Dictionary.

• To break off; interrupt; disturb.
• 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.
• Figuratively, sudden; without notice to prepare the mind for the event; unceremonious: as, an abrupt entrance or address.
• Lacking in continuity; having sudden transitions from one subject to another: as, an abrupt style.
• In botany, terminating suddenly: as, an abrupt point: sometimes used in the sense of truncate: as, an abrupt leaf.
• noun An abrupt place; a precipice or chasm.

from the GNU version of the Collaborative International Dictionary of English.

• noun Poetic An abrupt place.
• transitive verb obsolete To tear off or asunder.
• adjective Broken off; very steep, or craggy, as rocks, precipices, banks; precipitous; steep.
• adjective Without notice to prepare the mind for the event; sudden; hasty; unceremonious.
• adjective Having sudden transitions from one subject to another; unconnected.
• adjective (Bot.) Suddenly terminating, as if cut off.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective extremely steep
• adjective surprisingly and unceremoniously brusque in manner
• adjective marked by sudden changes in subject and sharp transitions
• adjective exceedingly sudden and unexpected