scordatura

In music, tuning of the violin or other string instruments temporarily to other intervals than the normal tuning, for the purpose of facilitating the playing of chords with certain intervals or altering the instrument's tone-quality. The music is still written as for the normal tuning (and fingering), so that the instrument becomes to that extent a transposing instrument (see transposition).

There are many examples of scordatura in the violin works of Biber; also a famous passage for solo violin in Mahler's Fourth symphony.