What is the definition of a swimming lap?

Answer 1

If track athletes actually ran back and forth at a length of 25 yards each way, I strongly feel they would count each length as one lap. Running one large circle differs from swimming a short distance and going back and forth that distance. Of course a giant circle start to finish is a lap. A short distance is not easily seen as the same.

I think it must depend on who taught you how to swim, but no one is going to convince me that a lap is 2 lengths of the pool. I count lap 1, lap 2, lap 3, lap 4 as 100 yards. Sue me :)