* Scab - a crust that forms over a wound
* Slab - a flat piece of something, like stone or concrete
* Crab - a type of crustacean
* Blab - to talk idly or indiscreetly
It's worth noting that "dab" can also be a verb meaning "to apply something lightly", and "dab" can also be a noun referring to a small amount of something.