mump
Mump (verb) means to speak in a way that is hard to make out.
Etymology
Perhaps borrowed through obsolete Dutch mompen (“to cheat, swindle, deceive”), according to Kroonen, a derivative of Proto-Germanic *mump- (“to stain”), perhaps from Proto-Indo-European *mm̥bʰ-neh₂- Also akin to German mimpfeln (“to mumble”), Icelandic mumpa (“to take into the mouth”). See also English mum. While Kroonen claims Ancient Greek μέμφομαι (mémphomai, “I blame, accuse”) and the Germanic forms are reconcilable and related, Beekes rejects this, stating that Germanic -p- cannot here correspond to Greek -φ- and that this etymological connection is not widely considered reliable.