(US 美 triangle) noun [C] an instrument for drawing straight lines and angles, made from a flat piece of plastic or metal in the shape of a triangle with one angle of 90° （制图用的）三角板
setbacksetback
/ˈsetbæk ||; ˈsɛtˌbæk/noun [C] a difficulty or problem that stops you progressing as fast as you would like 障碍；挫折: She suffered a major setback when she missed the exams through illness.她因为生病而没能参加考试，遭受了重大挫折。