When you dilute something, you make it thinner, weaker or more watered down. Like ice-cubes melting into your soda — it totally dilutes the bubbly taste!
Think about diluting as lessening the quality but increasing the quantity. Unless you're diluting a really strong drink to make it taste better or diluting heavy paint to get a lighter shade — then the quality actually improves. Quipped President John F. Kennedy, “Public speaking is the art of diluting a two-minute idea with a two-hour vocabulary.”