Learner's definition of DIRT
a substance (such as mud or dust) that makes things unclean
You've got some dirt on your face.
Their shoes were covered with dirt.
No amount of cleaning will get rid of all this dirt.
a person or thing that has no value
information about someone that could harm the person's reputation
◊ To dig up (the ) dirt on someone is to find out information that is harmful to that person's reputation.
◊ To dish (the) dirt is to spread harmful gossip or information.
in the dirt
◊ In baseball, a pitch is in the dirt when it hits the ground near home plate before reaching the catcher.