Xinca (or Xinka, Sinca, or Szinca) is a small extinct family of Mesoamerican languages; formerly, the language was regarded as a single language isolate. Xinca was once spoken by the Indigenous Xinca people in southeastern Guatemala, parts of El Salvador, and Honduras.

They have also historically been referred to as Popoluca or Popoluca-Xinca; Popoluca being a Nahuatl term for unintelligible speech.

The Xincan languages have no demonstrated affiliations with other language families. Lehmann (1920) tried linking Xincan with Lencan, but the proposal was never demonstrated. An automated computational analysis (ASJP 4) by Müller et al. (2013) also found lexical similarities between Xincan and Lencan. However, since the analysis was automatically generated, the grouping could be either due to mutual lexical borrowing or genetic inheritance.

The Xincan languages were formerly regarded as one language isolate. However, the most recent studies suggest they were indeed a language family.

There were at least four Xincan languages, each of which is now extinct. Yupiltepeque was spoken in Jutiapa Department, while the rest were spoken in Santa Rosa Department. Campbell also suggests that the Alagüilac language of San Cristóbal Acasaguastlán may have in fact been a Xincan language.

To these, Glottolog adds

Sachse (2010) considers all Xincan speakers today to be semi-speakers, with the completely fluent speakers having already died.

Xincan languages have many loanwords from Mayan languages especially in agricultural terms, suggesting extensive contact with Mayan peoples. According to Campbell, Xinca also has a "vast number of Mixe-Zoquean loanwords", suggesting contact with now extinct Mixe-Zoque varieties of the Guatemalan Pacific coast.