1) A food cart found at a festival
2) A float pulled/drawn as part of a mikoshi procession during a festival
The difference in the usage of the term seems to be regional. #2 is used in the Chichibu area, for example, for the Chichibu Yo-matsuri (hence the well-known festival music Chichibu yatai-bayashi). However, in other parts of Japan dashi seems to be a more common term for definition #2.