adjective/ɛ̃.tɛʁ.kɔ̃.pʁe.ɑ̃.sibl/
mutually intelligible, intercomprehensible (that can be mutually understood by each other's speakers)
“Le letton et le lituanien ne sont pas intercompréhensibles.” — Latvian and Lithuanian are not mutually intelligible.
Related: intercompréhensibilité
From inter- + compréhensible.