Although reticence has acquired a sense synonymous with that of reluctance, it’s important to maintain an important distinction between the two terms.
Reticent means “disinclined to communicate or speak,” or “restrained in appearance or presentation.” Reluctance, by contrast, refers to an aversion, hesitation, or unwillingness to do or say something. Thus, although one might say, for example, that one is reluctant to be critical about another person, one might be reticent about revealing one’s thoughts in a given situation or in general. By contrast, one is not generally reluctant by nature.
Two other words that also start with re- and have similar meanings invite further confusion. Reserve, among various definitions, means “caution or restrain about what one does or says, or an avoidance of explanation or expression,” and this, too, might be specific to one issue or might be a personality trait. Meanwhile, one of the meanings of restraint is “the restriction of expression of emotions or thoughts,” which is situational rather than characteristic.
The sentences below illustrate the various shades of meaning among these words:
“Her reluctance to go on the boat stemmed from a childhood bout of seasickness.”
“Jane’s reticence about explaining where she had been made them suspicious.”
“His reserve implied arrogance and condescension.”
“John demonstrated admirable restraint in not arguing with Mary when she picked a fight with him.”
Restraint is appropriate only in the final sentence, and only restraint is appropriate there, but although the first three terms are interchangeable in the other sentences, each term is best suited for the specific connotation indicated in its respective sentence.