The story
- Proto-Indo-European · derived from*sem-“together”
- Latin · derived fromsincerus“genuine”
- Middle French · borrowed fromsincere
- English todaysincere
From Middle French sincere, from Latin sincerus (“genuine”), from Proto-Indo-European *sem- (“together”) (whence English sam) + *ḱer- (“grow”) (whence Latin Ceres, the goddess of harvest, etymon of cereal). Not from sine (“without”) + cera (“wax”), which is a folk etymology; see Wikipedia page.
Words from the same roots
Latinsincerus all →
Proto-Indo-European*sem- all →
Etymology from Wiktionary, CC BY-SA 4.0.