Edit: To add a bit of context here a lot of people are talking about pesticides and fertilizer and stuff like that but we don't do anything like that, we just mow it when it gets a bit long. Does that mean our lawn is technically a meadow?
A meadow, or natural lawn, or whatever you want to call it would be a mix of grass, clover, and other "weeds". It wouldn't require anywhere near as much chemical treatment (if any) and could be mowed and watered far less often. To me, it would also be allowed to grow long enough to flower, to promote pollinating insects.
I tend not to let the clover or dandelions flower though, as it attracts bees to the lawn, and barefoot children (very common in my country, and not looked down on like in the US) and bees on a lawn aren't a happy mix.
My garden is filled with heaps of flowering annuals and perennials though.