(Latin: sound; pure, clean, whole, genuine, untainted)

insincere (adjective), more insincere, most insincere
Pertaining to not being honest in the expression of one's actual feelings; hypocritical: After bumping into Celia in the store, Jack seemed to make an insincere apology because he rushed off without checking to see if he had hurt her.
insincerely (adverb), more insincerely, most insincerely
A reference to someone who pretends to feel something that is not really felt, or not meaning what he or she says: Hayden had the impression that the woman, who told him that he made a good speech, was insincerely expressing her opposition to his view points.
insincerity (s) (noun), insincerities (pl)
The quality of not being open or truthful but being deceitful or hypocritical: While talking to her parents about her marriage, Gill recalled the many insincerities her husband showed in their relationship.
Prompte et sincere. (Latin expression)
Translation: "Prompt and sincere."

Motto of Calvin Theological Seminary, Grand Rapids, Michigan, USA.

sincere (adjective); sincerer, more sincere; sincerest, most sincere
1. Honest and unaffected in a way that shows what is said is really meant: Fay made sincere efforts to do her best during her studies before the final exam.
2. Based on what is truly and deeply felt: Oliver showed his sincerest concern about his health by working out at the fitness studio as often as possible and striving to eat properly.
3. Free of deceit, hypocrisy, pretense, or falseness; earnest: Henry wrote a sincere apology for his critical statements during the business meeting.

Jason expressed his sincerest hope for Jill's recovery from her illness.

4. Etymology: Early senses (mid 16th century) of sincere included "not falsified" and "unadulterated"; the source is Latin sincerus, "clean, pure" and the notion "containing no deception" was also expressed early.
—Compiled from Oxford Dictionary of Word Histories;
Edited by Glynnis Chantrell; Oxford University Press;
Oxford, England; 2004; page 465.

Theories of the etymology of sincere

Several ideas have been advanced to explain the derivation of the word sincere, but none has been substantiated!

The most logical attributes the genesis of the word to the Latin sincerus, meaning "pure" or "clean"; but, many etymologists state that sincere is a compounding of sine cera, which means "without wax".

According to this "unverifiable etymology", in the time of the ancient Romans, devious dealers in marble and pottery would conceal defects in their products by filling the cracks and holes with wax and matching marble dust.

Honest merchants, who did not doctor their products, proudly displayed their wares as being "without wax"; that is, they were sine cera.

It is unlikely that this is the origin of sincere; at any rate, accepting this theory should alert us to not forget another Latin phrase: caveat emptor!

—Compiled from information in
The Story Behind the Word by Morton S. Freeman;
iSi Press; Philadelphia, Pennsylvania; 1985; page 243.

Other "assumed origins" of sincere

This sneaky trick (rubbing wax into the cracks of marble works) came to the attention of the Roman Senate, which passed a law stating that all marble purchased by the government must be sine cera, "without wax".

From this law and this root, comes our modern word sincere, which means "without deceit".

—Compiled from
500 Years of New Words by William Sherk,
Doubleday Canada Limited, Toronto, Canada; 1983.

Sincere comes from an early period when middle-class Roman citizens wanted duplicates of fine art for their own smaller villas and gardens.

There was, at the time, a kind of "assembly line" of cheap sculptures produced from poorer grades of marble; and often in the manufacturing process, a nose, an ear, or a finger, would break off, which the sculptor would repair with paraffin wax mixed with marble dust.

For those who wanted to be sure that that they had the best quality, the artist would inscribe sine ceres on the bottom of the statue to certify that such a piece of work was fully genuine and "with no wax".

—Dr. W. C. Farmer, PhD, ThD

One more theory of the origin of sincere

Modern scholars do not accept the dubious account about sincere originally meaning "without wax".

The present belief is that the Latin sincerus, which became sincere in English, came from sine, "without", and some lost word that was akin to caries, "decay".

It would thus be synonymous with the Greek akeratos, "without taint".

—Based on information from
Thereby Hangs a Tale by Charles Earle Funk,
Harper & Row, Publishers, New York, 1950.
sincerely (adverb), more sincerely, most sincerely
1. In an honest and unaffected way: Shirley sincerely told her parents everything about her feelings regarding her marriage relationship.
2. A written formula for ending a message: Expressing "Yours sincerely" is often used immediately before the signature at the end a letter or an e-mail, which is addressed to someone by name; another example is "Sincerely yours, Jim Mason".
sincerity (s) (noun), sincerities (pl)
The quality or condition of being honest and without duplicity: Harry's sincerity was shown by what he did to help his neighbor and not by merely wishing him "good luck".

Everyone in the office was touched by the sincerity expressed by the supervisor, Mr. Hayes, who had to reduce the number of staff members as a result of poor economic conditions.