sincere

Etymology

First recorded in the 1530s,^[1][2] borrowed from Middle French sincere,^[2][3] from Latin sincērus (“whole, clean, pure; genuine”),^[1][4] a word of uncertain origin.^[1] It may come from Proto-Indo-European *sem- “one” + the root of Latin crēscere “to grow”, i.e. originally “of one growth, unmixed”.^[1][2][3]

The popular story that it means “without wax” (Latin sine cērā) has no etymological justification.^[4][1][3]

References

1. [1] [2] [3] [4] [5] Harper, Douglas, Online Etymology Dictionary, https://www.etymonline.com
2. [1] [2] [3] Merriam-Webster's Collegiate Dictionary, Springfield, Mass.: Merriam-Webster
3. [1] [2] [3] Wiktionary, the free dictionary, https://en.wiktionary.org
4. [1] [2] Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press