Most websites (including Wikipedia) say that the anion MoO42- is called a molybdate ion, although some websites use molybdenate instead. Which one is correct, and if one of them is correct, is the other term still allowed?
If you do a Google ngram of the terms 'molybdate' and 'molybdenate', you will find 'molybdate' standing out.
No one known why the 'en' was kept when you can simply shorten it to molybd-ate instead of molybden-ate (like phosph-ate and not phosphor-ate). However, the latter didn't got totally eliminated. Some research papers(here is a recent example) and textbooks still uses 'molybdenate'. The following image is from a physics textbook published in 2020.