The sudden (timescale of minutes to hours) disappearance of a solar FILAMENT (PROMINENCE).
ON-LINE GLOSSARY OF SOLAR-TERRESTRIAL TERMS of National Geophysics Data Center

A solar filament (prominence) that disappears suddenly (on a time scale of minutes to hours). The prominence material is often seen to ascend but is also seen to fall into the Sun or just fade. (Historically, DSFs have been called disparitions brusques because they were first studied by French astronomers.) DSFs are a possible indicator of coronal mass ejections.