blotch

blotch
/blɔtʃ; blɑtʃ/ n
large discoloured mark, usu irregular in shape (on skin, paper, material, etc) （皮肤、纸张、材料等上的）大斑点
    His face was covered in ugly red blotches. 他脸上有许多难看的红色大斑点.

牛津英汉双解词典