What average order value means
The metric describes buying behaviour per order, not per customer and not per visit. Someone who makes four small purchases in a month contributes four low-value orders, even if their commercial value is high. That is why AOV replaces neither customer lifetime value nor revenue per user, which answer different questions.
The delicate part is the word revenue. Google Analytics 4 keeps the concepts apart: item revenue excludes taxes and shipping costs, while total revenue in the monetisation report already subtracts refunds. Two legitimate figures that produce two different AOVs from exactly the same orders.
There is no single definition of an order either. Some shops count every confirmed transaction, others exclude the ones cancelled before dispatch, and those selling subscriptions have to decide whether each renewal is a new order. As long as the definition stays stable inside the same shop, the time series is usable. The moment it is compared against a competitor or an industry report, the comparison turns fragile, because what went into the numerator is almost never published.
It is worth remembering that this is an arithmetic mean and therefore sensitive to outliers. A handful of wholesale orders lifts the monthly AOV without anything having changed in the behaviour of the usual buyer. The median order amount, calculated alongside, exposes that effect immediately.