These words mean free from pretence, concealment, reservation or falsehood. Sincere is the most general of these and the most positive in tone, suggesting a complete absence of hypocrisy and an exact identity between appearance and reality, with added implications of friendliness, interest and kindness: a sincere expression of gratitude that went beyond mere formality. Honest and genuine stress truthfulness. Honest may be considerably more neutral than sincere and may describe an isolated instance of truth-telling as easily as it suggests an unvarying character trait: even the least sincere hypocrite occasionally makes an honest statement. Genuine is closer to sincere than honest in its positive warmth of tone, emphasizing that a person or thing is really what it seems: He showed genuine regret. In another sense, someone may be genuine and neither honest nor sincere : a genuine confidence man.

The Australian term dinkum and the rarer dinky-di seem to be going out of general use, but have been preserved colloquially in certain contexts. When applied to persons, they are almost synonymous with sincere and genuine in the implication of being what one seems; He is a dinkum (or dinky-di ) Aussie. Occasionally they may be applied to things when the above connotation of genuine is intended: This is a dinkum black opal. The most frequent present use of dinkum is adverbial, when the sense of truly or really is suggested: He will be here tomorrow ?dinkum .

Open and unfeigned suggest, negatively, a refusal to play roles that might conceal one’s true nature and positively, a willingness to risk exposure and to tell all one knows. Open emphasizes telling the whole truth: begging her to be open with him, even if she disapproves of him. It suggests fearlessness of the consequences and can veer over into suggesting an unnecessary or hurtful frankness: to show open hostility. Unfeigned does not necessarily suggest that the complete truth is told or expressed, but it does indicate a lack of posturing or archness: unfeigned delight in being with him, despite her suspicions about his behaviour. Sometimes it may suggest a sudden or unwilling revelation of one’s true feelings: an irrepressible outburst of unfeigned disgust.

Heart-felt and whole-hearted stress that aspect of sincere that pertains to warmth of concern and deepness of kind or friendly feelings. Heart-felt can indicate a rare inward intensity that is assented to completely: giving her his heart-felt sympathy. The word is in some danger of seeming too flowery in many instances. Whole-hearted escapes this danger, with its suggestion of thoroughgoing dedication without reservation, or an undivided response to experience: giving the proposal our whole-hearted approval. The word also suggests emotional exuberance or enthusiasm: whole-hearted merrymaking.

Often, sincere appears linked with another word here as a clarifying intensification, as though the word were limited in its force. "Sincere and genuine " seems to suggest that even sincerity by itself can be pretended; "sincere and honest " suggests that one can be sincere in one’s intentions and yet be in error or fail to give the whole truth; "sincere and open " suggests that one could be concerned and honest and still be shy and reserved or hold back something of importance. Light is also cast on the felt limitations of sincere by another common type of doublet: sincere but mistaken; sincere but misguided; sincere but ill-tempered. These phrases imply that one may mean well and still fail to do the right thing because of a lack of knowledge, understanding or control of one’s emotions.