- Language: Siuslaw
- Alternate names: Umpqua, Ku-itc (Kuitsh)
- Language code: sis
- Language family: Language isolate (SIL classification)
- Number of speakers: Ø
- Vulnerability: Dormant
No speakers by the 1970s (Golla 2007). No speakers of Siuslaw for many years (1998 M. Kinkade).
Siuslaw (proper) and Lower Umpqua are two closely related dialects. There have been no known native speakers since the 1970s.