People do always say 為之 [wai4 zi1] that does not mean “define”. I suspect that they actually mean 謂之 [wai6 zi1] that fits the meaning of “define”.
However, there is no reason that native speakers could not discern the difference in tone between the two (tone 4 vs tone 6).
I too want to know the correct answer to your good question.
However, there is no reason that native speakers could not discern the difference in tone between the two (tone 4 vs tone 6).
I too want to know the correct answer to your good question.