Umai is kind of difficult to translate properly, it's not just "delicious", there's a bit more to it. From what I gathered it's more of a mood thing than a taste thing, basically the experience you had with your food. Like, an ice cream on a cold day is not as umai as on a hot day, even though the taste is the same regardless of weather.
Wait, my bad, I was thinking of oishii, that's the complicated term that usually gets translated as simply "delicious". Umai on the other hand is straightforward, it does indeed mean tasty or delicious and is used to directly describe taste.
