silent, taciturn, reticent, reserved, secretive mean showing restraint in speaking. silent implies a habit of saying no more than is needed.
// the strong, silent type taciturn implies a temperamental disinclination to speech and usually connotes unsociability.
//taciturn villagers reticent implies a reluctance to speak out or at length, especially about one's own affairs.
// was reticent about his plans reserved implies reticence and suggests the restraining influence of caution or formality in checking easy informal conversational exchange.
// greetings were brief, formal, and reserved secretive, too, implies reticence but usually carries a suggestion of deviousness and lack of frankness or of an often ostentatious will to conceal.
// the secretive research and development division