A "trill" is a musical ornament consisting of a rapid oscillation between a given tone and the tone immediatetly above it (and sometimes below it) in the scale. It can be indicated by the abbreviations t. or tr. placed above a given note, or by a graphic sign: ~.
In the closing section of the exposition, in the first movement of his Fifth Symphony, Beethoven uses the trill in a relatively slow motion, thus enhancing the dramatic atmosphere.
