@tchrist I believe it was a mistake (or at least an instance of jumping the gun) to migrate 'Why do we call it a “positive definite matrix” rather than a “positively definite matrix”?' to the History of Science and Mathematics (HSM) SE.
If you read my answer (which is now posted on HSM), it seems that there are good, purely linguistic reasons for why it's *definite* as opposed to *definitely*. In any case, my answer is completely linguistic.
Assuming the answer I posted is judged to be valid (or at least a valid part of the full answer), it would seem to follow that although the questio…