Coal·sack 
(kōlsăk′)
(kōlsăk′)n.
1. A dark nebula, one of the nearest to Earth, that appears in the southern Milky Way.
2. A similar dark nebula in the Northern Hemisphere near the constellation Cygnus.
- senescence
- senescent
- seneschal
- Senghor
- senile
- senile dementia
- senilely
- senility
- senior
- senior airman
- senior chief petty officer
- senior citizen
- senior-citizen
- senior citizenry
- senior high school
- senioritis
- seniority
- senior lecturer
- senior master sergeant
- senior moment
- seniti
- Senlac
- senna
- Sennacherib
- sennachie