plural of knight-errantry

The character or actions of wandering knights; the practice of wandering in quest of adventures. / Chivalry; a quixotic or romantic adventure or scheme.

Obsolete form of errant.

(obsolete) Liable to error; fallible.

The quality of being erratical.

The quality of being erratic.

(education) The distinction drawn by some language teachers between an "error" (a mistaken belief that a given usage or construction is correct; or, an incorrect use resulting from such a belief) and "a mistake" (an accidental use of a usage or construction despite knowing that it is incorrect).

plural of erration

(obsolete, rare) Wandering or straying.

(mathematics, statistics) A sigmoid function giving the probability that a measurement, under the influence of normally distributed errors with standard deviation, is within a certain distance from the mean value.