Sincere, pure, or genuine
Cincere is a modern phonetic variant of the English word 'sincere'. It is part of a contemporary American trend of using virtue names with creative spellings to provide a unique identity while maintaining a traditional moral meaning. The root word derives from the Latin 'sincerus', which historically meant clean, pure, or sound.
Less common today
Cincere isn't in the latest US Top 1000. It last peaked at #2,754 in 2002.
US births per 5-year period, 1990βpresent (SSA data).