Whats the definition of alkaline and acid?

Well, if 7 is neutral, which would be like water, then acid is sour and alkaline is sweet. Neither is 'bad' but as they go farther up and down the scale, the more concentrated they are to the point of doing damage to things around them (think sulfuric acid). Soda has acid in it, ascetic acid is in a lot of things we eat and drink. As for alkaline, Comet cleaner is alkaline, lye soap is alkaline.