abrupt - adj.
1 sudden and unexpected; hasty (his abrupt departure).
2 (of speech, manner, etc.) uneven; lacking continuity; curt.
3 steep, precipitous.
4 Bot. truncated.
5 Geol. (of strata) suddenly appearing at the surface.

abruptly adv. abruptness n. [L abruptus past part. of abrumpere (as AB-, rumpere break)]