sincerus

• syncerus (Medieval Latin)

From Proto-Italic *senkairos, from Proto-Indo-European *sem- (compare Latin simplex, and Sanskrit सम (sama, “whole, together”)) and *ḱer- (“grow”) (compare Sanskrit किर् (kir, “pour out”)). According to De Vaan, the second part of the compound derives from the unattested adjective *caerus found in the first part of caerimōnia, which is also related to caelum (“sky”).^[1] However, this is problematic: the expected outcome of Proto-Italic *senkairos would be *sincīrus, since Proto-Italic /ai/ gives /iː/, not /eː/ under vowel reduction (as in occīdere), and it is implausible that this word was imported from rural dialects of Latin which monophthongize /ai/ to /ɛː/, as in fēnum, without leaving any trace of the urban Latin development.

• (Classical Latin) IPA^(key): /sinˈkeː.rus/, [s̠ɪŋˈkeːrʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /sinˈt͡ʃe.rus/, [sin̠ʲˈt͡ʃɛːrus]

sincērus (feminine sincēra, neuter sincērum, comparative sincērior, adverb sincērē or sincēriter); first/second-declension adjective

1. clean, pure, sound
2. uninjured, whole
3. real, natural
4. genuine, sincere

First/second-declension adjective.

• īnsincērus
• sincēritās

• “sincerus”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “sincerus”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• sincerus in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
• Walther von Wartburg (1928–2002) “sincērus”, in Französisches Etymologisches Wörterbuch, volumes 11: S–Si, page 640