Why is sinus called sinus?

1) Because if you spell sinus backwards, it becomes sinus which in latern means inter galctual head smetis.

2) According to my knowledge, the 'sinus' was originally called the 'inf-inf' based on its anatomical root, however as medicine evolved, it led to many misdiagnosed cases of speech impairments and hours of unnecessary therapy for sick patients who would visit the town doctor or shaoman and seek treatment for their inf-inf infection. Once this complication was recognized, it was renamed to avoid future confusion using the name of the discovering doctor, Mr. Sinus Smetis.