In japanese, expression showing the full satisfaction obtained by eating, drinking or tasting anyway, somethings really delicious (delicious is what oishii properly means), mostly, but not necessarily, related to food or drink.
Coming from the Imperial Family and the noble class of the Heian period (794-1185 AC), it's still mainly used among highly educated people and academic circles, as a way of very polite and formal appreciation, sometimes just in order to mark the intellectual superiority from the common way of speaking.
Adjective describing the pleasant condition of time or situation possible to be spent without stress, nuisance, or any other disturbing or bothering element.
This word probably origins, in far east Asia's workers slang, from the name of a managing level staff so troublesome to make colleagues and subordinates down just by his presence.
We enjoyed a lot on the beach yesterday : shining but not hot at all, a light breeze blowing and just a few people around, great ! It was such an aiba-less day !