In the Russian language of the 19th century (and earlier) Estonians were called Cudj. There are some publications that claim that the Latvian family name Cudars was made of this ethnonim. I have not heard, however, that this ethnonim was ever used in Latvian.

Further Reading

Names of ethnicities and ethnicities in names - Bruno Martuza-ns. 2002


The origin of the name 'cudars'
"in the 19th century, people who lived in neighboring parishes referred to the residents of Ma-rciems as Chuds. In all of Latgale except its southernmost regions, there are many surnames and toponyms with the root cu-dar-, cudar- and codar-. Examples include the surnames Cudars in Vil,aka, Cudars in Nautre-ni and Codars in Cibla" Antons Breidaks

Further Reading

ETHNO-LINGUISTIC CONTACTS - Antons Breidaks