语言灭亡（英语：language death、language extinction、linguistic extinction、linguicide、glottophagy）是一个影响语言社区的过程。这现象显示某项语言变体的讲者族群，相关之语言能力呈下降迹象，最终造成没有母语者或流利讲者承继，导致相关语言绝迹。语言灭亡会同时影响不少相关细项，包括方言及文本等的传承。有关现象与只有部分言语丧失的语言消耗截然不同。

In linguistics, language death (also language extinction, linguistic extinction or linguicide, and rarely also glottophagy) occurs when a language loses its last native speaker. Language death is a process that affects speech communities where the level of linguistic competence that speakers possess of a given language variety is decreased, eventually resulting in no native or fluent speakers of the variety. Language death may affect any language idiom, including dialects and languages. Language death should not be confused with language attrition (also called language loss), which describes the loss of proficiency in a language at the individual level.