In the sentence
'The' is one of the most frequently used words in the English language.',
if I deleted the word 'frequently' wouldn't the meaning of the sentence be unchanged? If this is the case, is the expression 'most frequently' right? Wouldn't the word 'frequently' be redundant? I argued with someone that the expression 'most frequently used' is incorrect (or atleast unnecessary).
I want to know if there is a difference between the two, and if not, which one is a better choice. Thanks in advance.