If you walk unevenly, you have a limp. Maybe you pulled your hamstring at the annual Thanksgiving Day Football Showdown, or maybe one leg is three inches shorter than the other. Whatever the reason, if your gait is off kilter, you limp.
You can have a limp (the noun), or you can limp (the verb), and both mean that for some reason your legs don’t work quite in synch. Limp can also be an adjective that means "not strong or firm," like your friends' limp response to your invitation to come help paint your house or when your hair looks limp, meaning it's just hanging, with no volume or style.