a curve like the path of an object thrown into the air and falling back to earth 抛物线 
A ball thrown over a long distance travels in a parabola. 球扔出很远，在空中划出一道抛物线。
Word Originlate 16th cent.: modern Latin, from Greek parabolē ‘placing side by side, application’, from para- ‘beside’ + bolē ‘a throw’ (from the verb ballein).
