Both the American Heritage and Merriam-Webster’s dictionaries now accept “reluctant” as a meaning of reticent. If we accept this, the very useful distinction between the two words is lost and I am faced with one more subtlety my coconversationalists will miss.
Reticent only means “reluctant to speak” in the rest of the English-speaking world. It has been misused in the US by people trying to show off vocabularies they have not mastered so long that we are being forced to give up the distinction between this meaning and “reluctant to act”, which we already have in reluctant and hesitant.
The -tic-ent in reticent is based on the same root as that in tacit, a stem based on the Latin verb tacere “to be silent”. We don’t need another synonym for reluctant and hesitant and we do need a verb which means simply “[r]eserved; disinclined to speak freely; given to silence or concealment,” the only definition given by the Oxford English Dictionary.
I am too old to give up the distinction and recommend others maintain it, too. It makes no sense to surrender the subtleties with which the richness of our vocabulary provides us.