An abrupt change in slope. A point on a stream profile where a change in gradient occurs. This could be caused by a change in underlying bedrock or bedrock structure.

A point of significant or abrupt change stream gradient, often attributed to headward erosion related to baselevel change or tectonic uplift

a point of abrupt change or inflection in the longitudinal profile of a stream or of its valley. It is usually a waterfall or a set of rapids.

A location in the stream where there is a sharp change in the slope of the channel such as a waterfall (steep slope) or lake (no slope).

A sudden vertical drop in the longitudinal profile of a stream; usually indicative of a headcut or waterfall.

A knickpoint is a term in geomorphology to describe a location in a river or channel where there is a sharp change in channel slope, such as a waterfall or lake, resulting from differential rates of erosion above and below the knickpoint. Sharp changes in channel slope caused by faulting or in-channel construction are not considered knickpoints.