Unarmed Strike
Instead of using a weapon to make a melee attack, you can use a punch, kick, headbutt, or similar forceful blow. In game terms, this is an Unarmed Strike—a melee attack that involves you using your body to damage, grapple, or shove a target within 5 feet of you. Whenever you use your Unarmed Strike, choose one of the following options for its effect. Damage. You make an attack roll against the target. Your bonus to the roll equals your Strength modifier plus your Proficiency Bonus. On a hit, the target takes Bludgeoning damage equal to 1 plus your Strength modifier. Grapple. The target must succeed on a Strength or Dexterity saving throw (it chooses which), or it has the Grappled condition. The DC for the saving throw and any escape attempts equals 8 plus your Strength modifier and Proficiency Bonus. This grapple is possible only if the target is no more than one size larger than you and if you have a hand free to grab it. See also “Grappling.” Shove. The target must succeed on a Strength or Dexterity saving throw (it chooses which), or you either push it 5 feet away or cause it to have the Prone condition. The DC for the saving throw equals 8 plus your Strength modifier and Proficiency Bonus. This shove is possible only if the target is no more than one size larger than you.
Unconscious [Condition]
While you have the Unconscious condition, you experience the following effects. Inert. You have the Incapacitated and Prone conditions, and you drop whatever you’re holding. When this condition ends, you remain Prone. Speed 0. Your Speed is 0 and can’t increase. Attacks Affected. Attack rolls against you have Advantage. Saving Throws Affected. You automatically fail Strength and Dexterity saving throws. Automatic Critical Hits. Any attack roll that hits you is a Critical Hit if the attacker is within 5 feet of you. Unaware. You’re unaware of your surroundings.
Unoccupied Space
A space is unoccupied if no creatures are in it and it isn’t completely filled by objects.
Utilize [Action]
You normally interact with an object while doing something else, such as when you draw a sword as part of the Attack action. When an object requires an action for its use, you take the Utilize action.