Translation Error Rate (TER)

Translation Error Rate (TER) basically measures the amount of editing that a linguist would need to perform in order for a translation to match a reference (human) translation.

Translation Error Rate (TER) is a metric for automatic evaluation of machine translation that calculates the number of edits required to change a machine translation output into one of the references.

TER corresponds to post-editing effort.

(https://machinetranslate.org/ter)