I suppose there was a misunderstanding, because he told me on the phone that he had arranged with you to come next week.

misunderstanding 是由前缀 mis-（表示“错误”）和 understanding（理解）组成的复合名词。mis- 表示“错误”或“不正确”，understanding 是“理解”的意思。所以 misunderstanding 的字面意思是“错误的理解”，即“误解”。