Function whose domain is between -1 and 1

• 30°, for 0.5
• Inverse trig function
• Trig angle
• Inverse math function
• Trig function
• Inverse trigonometric function
• It's measured in radians
• Function of math class

Wiktionary Word definitions in Wiktionary
n. (context trigonometry English) Any of several single-valued or multivalued functions that are inverses of the sine function. Symbol: arcsin, sin -1