trapezium  
noun [ C ]  specialized uk/trəˈpiː.zi.əm/ us/trəˈpiː.zi.əm/  trapezia uk/trəˈpiː.zi.ə/ us/trəˈpiː.zi.ə/ trapeziums
  (SHAPE)         
  mathematics UK梯形 
a flat shape with four sides, where two of the sides are parallel
 Synonym: trapezoid (SHAPE) 
  mathematics US不规则四边形 
a flat shape with four sides, where no sides are parallel
 Synonym: trapezoid (SHAPE) 
   (BONE)     
 anatomy 大多角骨
a bone in the wrist at the base of the thumb