prolusion

A preliminary exercise.

An essay written as a preface to a more detailed work.

A prelude to a game, performance, or entertainment; hence, a prelude, introduction, or preliminary in general.

An essay or preparatory exercise in which the writer tries his own strength, or throws out some preliminary remarks on a subject which he intends to treat more profoundly.

A trial before the principal performance; a prelude; hence, an introductory essay or exercise.

A trial before the principal performance; a prelude.

An introductory essay.

a short introductory essay preceding the text of a book

exercising in preparation for strenuous activity