Is “Sinus” a Scrabble word?
Yes
SINUS
Valid in at least one Scrabble dictionary
Valid in these dictionaries
SOWPODS / CSW
Scrabble UK & International
TWL / NWL
Scrabble North America
Large English Dictionary
General English word list
Meaning of Sinus
/ˈsaɪnəs/
noun
1.A pouch or cavity in any organ or tissue, especially the paranasal sinus.
2.A channel for transmitting venous blood.
3.A notch or depression between two lobes or teeth in the margin of an organ.