A player or monster that is stunned has lost control over its movements. Stunning is a distinct condition from confusion but has similar effects.
The most noticeable effect of stunning on you is that whenever you try to choose a direction—to move, fire, zap, apply some tools, et cetera—a random direction will be selected instead. If you press a movement key you will always attempt to move, even if the direction attempted is blocked, say by a wall. You will not be prompted for confirmation before attacking a peaceful or tame monster on an adjacent square, so as long as you are stunned there is a risk of accidentally angering peaceful monsters or abusing pets.
Other effects of being stunned:
- You can only throw or launch one projectile at a time. It will probably not go in the direction you intended.
- You will be unable to control your teleports.
- If you throw Mjollnir, you will be unable to catch it.
Unlike confusion, there are few, if any, practical reasons to get yourself stunned.
- Becoming nauseous as an effect of eating tripe, rotten eggs, rotten tinned food, etc.
- Attempting to cast a forgotten spell (can also confuse you)
- Applying a cursed unicorn horn
- Opening or breaking a trapped door
- Opening a cursed tin that turns out to be trapped
- Triggering a mind-altering gas container trap
- Eating the corpse of a bat (any type) or stalker
- Polymorphing into a bat or stalker
- The Stun monster spell
- The passive attack of a yellow mold
- The melee attacks of an abbot or Demogorgon
- The gaze attacks of Baalzebub and Archons
- Reading a cursed scroll of destroy armor while wearing cursed -7 armor
- Trying to eat a rustproof item while polymorphed into a rust monster
Stunning can be cured by the following actions:
- Applying an uncursed or blessed unicorn horn
- Praying (stunning counts as a minor trouble)
- Waiting for it to wear off
The duration of stunning can be shortened by the following:
- Eating a lizard corpse will set the stun counter to 2
- Getting blinded by an Archon while not wearing the Eyes of the Overworld will set the stun counter to 1 to 3 
- Getting stunned by a monster casting stunning while having magic resistance or free action will set the counter to 1 
Stunning has a less significant effect on monsters than on the player. It has the following effects:
- You (and only you) receive a +2 bonus to hit stunned monsters.
- Stunned monsters cannot block or evade your kicks.
- Stunned monsters are immune to your gaze attacks.
- Stunned monsters are less likely to jump out of the way of a falling portcullis or off a closing drawbridge.
- Stunned peaceful humanoids react differently when you #chat with them.
- Stunned spellcasting monsters are more likely to cast undirected spells, just as they would if they weren't adjacent to you. If they do this, they still get their normal turns, however.
Stunning does not cause a monster to move randomly or miss turns.
A user has suggested improving this page or section as follows:
"Needs a new reference for bat/stalker stunning."
- You stagger...
- You became stunned, from an explosion or spell.
- You wobble in the saddle.
- You became stunned while riding.
- You can't seem to think straight.
- You became stunned from nausea.
- You feel a bit steadier.
- Your stunning wore off.
- You feel less wobbly now.
- Your stunning wore off, while you were hallucinating.
- Stunning is one of the possible effects of eating a mushroom or pink pill.
- The glowing eye, bloodshot eye, the Beholder, and Planetar and Solar have stunning gaze attacks. The byakhee and astral deva have stunning melee attacks, and the yellow jelly has a stunning passive attack.
- Stunning can be cured by eating a white pill from a medical kit (if you are not already sick, blind, hallucinating, vomiting or confused, and if the pill does not fail) or by praying (not sitting) on a toilet.
- You cannot use the research technique while stunned.
- src/dothrow.c in NetHack 3.6.0, line 1174
- src/mhitu.c in NetHack 3.6.0, line 2109
- src/mcastu.c in NetHack 3.6.0, line 455
- src/potion.c in NetHack 3.6.0, line 99
- src/potion.c in NetHack 3.6.0, line 97
- src/potion.c in NetHack 3.6.0, line 92