Definition of the word account for

The phrase "account for" originated in the Middle English language during the 14th century. At that time, it was used to mean "pay for" or "reimburse for." However, as the English language evolved, the meaning of the phrase changed eventually. The current meaning of "account for" is to explain or provide a reason for something. This usage of the phrase began in the mid-16th century, and it's believed to have originated from the accounting practice of creating a record, or "account," of all receipts and expenses for a particular event or transaction. When trying to understand or make sense of something, people began to ask, "what account does this fall under?" or "what account can be made for this?" Thus, "account for" came to mean "explain" or "provide a reason" for something.