From SRD 5.2.1
Condition
A condition is a temporary game state. The definition of a condition says how it affects its recipient, and various rules define how to end a condition. This glossary defines these conditions:
Blinded
Charmed
Deafened
Exhaustion
Frightened
Grappled
Incapacitated
Invisible
Paralyzed
Petrified
Poisoned
Prone
Restrained
Stunned
Unconscious
A condition doesn't stack with itself; a recipient either has a condition or doesn't. The Exhaustion condition is an exception to that rule. See also chapter 1 ("Conditions").