|Sound change and alternation|
Quantitative metathesis (or transfer of quantity) is a specific form of metathesis or transposition (a sound change) involving quantity or vowel length. By this process, two vowels near each other – one long, one short – switch their lengths, so that the long one becomes short, and the short one becomes long.
In theory, the definition includes both
but Ancient Greek, which the term was originally created to describe, displays only the former, since the process is part of long-vowel shortening.