Related Clues:

• It has a period of 2(pi)
• Indefinitely, with no appointed date - . . . . die
• Latin tag for indefinitely - . . . . die
• Without this it could be mathematical
• Trig class ratio
• Calculation done on radians
• Serving of venison sent back in the function
• Function of angle to disappear indefinitely
• Indispensable condition
• Word with curve or wave
• Right-triangle ratio
• Math wave
• Trigonometrical function
• ''__ invidia'' (unenvied: Lat.)
• Cosecant's opposite