Synonyms and related words :
Olympian, aloof, backward, bashful, blank, chilled, chilly, close, close-lipped, close-tongued, closemouthed, cold, constrained, cool, detached, discreet, distant, expressionless, forbidding, frigid, frosty, guarded, icy, impassive, impersonal, inaccessible, introverted, modest, offish, quiet, remote, removed, repressed, reserved, restrained, retiring, shrinking, shy, silent, standoff, standoffish, subdued, suppressed, taciturn, tight-lipped, timid, unaffable, unapproachable, uncommunicative, uncongenial, undemonstrative, unexpansive, ungenial, unresponsive, withdrawn