incidentとincidence

名詞「incident」と「incidence」はつづりも発音もよく似ていますが、意味は大きく異なります*。以下に2語の定義と正しい用法を例示します。

incident:（好ましくない）出来事。

(1) In that incident, the level of contamination was between 6 and 16 ppm.

(2) Most such incidents result in miscarriage.

incidence:（病気などの）発生、発生率。

(3) The incidence of both of these diseases increased in the U.S. between 1994 and 2007.

(4) The city has implemented measures to reduce the incidence of accidents at this intersection.

*2語ともここで例示する以外にもいくつか意味がありますので、ご注意ください。