This is the 242nd most frequent Czech word.
ať
"Let" or "so that."
Used to express a wish or hope for someone else
Ať je šťastný ve svém novém domě.
May he be happy in his new home.
Used to introduce an indirect command or request
Řekni mu, ať zavolá, až bude mít čas.
Tell him to call when he has time.
Used to express impatience or an urgent wish