Memento mori
Etymology
A Latin phrase meaning "remember that you must die," from "memento" (imperative of "meminisse," "to remember") and "mori" ("to die"). Rooted in Roman and Stoic thought, it became a genre of skulls, hourglasses, and wilting flowers in medieval and Baroque art. Flagged as a classical Latin phrase, not a modern coinage.
noun phrase · /muh-MEN-toh MOR-ee/
A reminder — often an object or image — of the certainty of death.
What it names
A handle for the deliberate practice of keeping mortality in view to sharpen how you live, and for a whole tradition of art built around it.
Example
He kept a small skull on his desk as a memento mori, a daily nudge not to waste the afternoon.
Related idea
Compare vanitas, its artistic cousin — still-life work dwelling on the emptiness of worldly things; a memento mori points more bluntly at death itself.