【Suave】 , 【urbane】 ,  【diplomatic】 ,  【bland】 ,  【smooth】 ,  【politic】  as applied to persons, their demeanor, and their utterances can mean conspicuously and ingratiatingly tactful and well-mannered.

These words at times can convey so strong a suggestion of insincerity or of a surface manner that their distinctive implications are obscured. It is chiefly in their nonderogatory use that essential differences in meaning are apparent.

【Suave】 suggests qualities that are or have the appearance of being acquired through discipline and training and that encourage or are intended to encourage easy and frictionless intercourse with others. Negatively, it suggests the absence of everything that may offend or repel; positively, it suggests such qualities as affability without fulsomeness, politeness without stiffness, and persuasiveness without evident desire to force one′s opinion on others.

【Urbane】 implies a high degree of cultivation, poise, and wide social experience; it also commonly suggests an ingrained or inbred courtesy which makes for pleasant and agreeable intercourse among all kinds of men regardless of their social or intellectual standing.

Since urbanity and an ability to deal with difficult or ticklish situations with great tact are theoretically the qualities of the typical diplomat, the adjective  【diplomatic】 , when used in reference to nondiplomats, carries these implications, often adding in addition a hint of artfulness in gaining one′s own ends.

【Bland】 is negative as well as positive in its implications, for it usually implies the absence of irritating qualities as strongly as it suggests serenity, mildness, and gentility. Nevertheless, in spite of this vagueness, the term often carries a hint of benignity or the appearance of it and usually directly implies an ingratiating pleasantness.

【Smooth】  differs from  【bland】 chiefly in being more positive in its implications and in being more consistently derogatory. Sometimes it stresses suavity, often an assumed suavity.

At other times it carries even a stronger implication of tactfulness and craft than  【diplomatic】 .

【Politic】  (see also EXPEDIENT ) when applied to persons implies both shrewdness and tact; the term usually suggests the ability to gain one′s ends or to avoid friction through ingratiating means or 【diplomatic】 methods. It varies considerably, however, in its implication of artfulness, sometimes connoting cunning or craft and sometimes little more than just the right degree of suavity.