Feasible - for something to make sense, to be realizable, possible, usefull.
"Let's design a car that can only drive 1 mph."
The above is not a feasible plan :)
Another way of saying 'doable', sexually speaking. Or if you're British, another way of saying someone is 'fit'.
Guy 1: Mannnnn, she's feasible.
Guy 2: Word, I'd definitely tap that.