/ˈsfɛnɔɪd/ SFE-noyd

Definitions

1. adjective

relating to or shaped like the Greek letter sigma

“The sphenoid bone in the skull is a unique shape.”

2. noun

a bone in the skull that is shaped like the Greek letter sigma

“The sphenoid bone plays a crucial role in the structure of the face.”

3. noun

a type of rock or mineral with a distinctive sigma shape

“The geologist carefully identified the sphenoid mineral.”