The Vedic mṛtyú, along with Avestanmərəθiiu and Old Persianməršiyu comes from the Proto-Indo-Iranian word for death, *mr̥tyú-, which is ultimately derived from the Indo-European root *mer- ("to die") and thus is further related to Ancient Greek μόρος and Latinmors.
Depart, Mṛtyu, by a different path; by that which is your own, and distinct from the path of the gods; I speak to you who have eyes, who have ears; do no harm to our offspring, nor to our male progeny.
Then he became a horse (ashva), because it swelled (ashvat), and was fit for sacrifice (medhya); and this is why the horse-sacrifice is called Ashva-medha [...] Therefore the sacrificers offered up the purified horse belonging to Prajapati, (as dedicated) to all the deities. Verily the shining sun [ye tapati] is the Asvamedha, and his body is the year; Agni is the sacrificial fire (arka), and these worlds are his bodies. These two are the sacrificial fire and the Asvamedha-sacrifice, and they are again one deity, viz. Death.