Defination of 'Creature'

Where can I find the official defination of "creature" in the rules? Tried searching D&D Beyond ot no avail, glanced through the players hand book and the basic rules but nothing jumped out, googling brings up a lot of fan sites but nothing official.

Playing with new players and the DM keeps being asked if each new monster is a "creature"; to my understanding "creature" is just a catch all term for any living thing to differentiate from "object" but that's just my understnading, I want to know where the actual defination is written down so I can read it and show it to them.

This is just one of those things they never bothered to write down an in-game definition of due to their idea of using natural language because they assume that everyone knows what a "creature" is already.

Quote from 2000AD >>

to my understanding "creature" is just a catch all term for any living thing to differentiate from "object" but that's just my understnading,

Yep, anything that's up and about and moving around. Any humanoid, beast, demon, undead, construct or whatever, even a mimic qualifies.

Creature is any monster or NPC usually coming with a type. Objects in comparison don't. 

If you're inquiring about a specific thing you're not sure about fell free to post it here and you will get an answer quickly.

The Monster Manual defines a monster as "any creature that can be interacted with and potentially fought and killed."

As others have wrote.  There really is no creature.  it is just a generic universal term to lump together things that appear in the books.

Creatures would be Beasts,  Undead,  Fey, etc...

I'd give creature as anything with grammatical animacy.

For gameplay mechanics, I think what we really want to know: What isn't a creature? To the best of my understanding, inanimate objects, wieldable/wearable/usable gear, empty ground, physical manifestations of spells (Cloudkill, Fireball, Wall of Fire and the like) that cannot be interacted with and slain/defeated. The campfire, the rations, the hemp rope, the Immovable Rod, the Staff of Power, and your character's underwear are all not creatures. Golems, undead, an artificer's eldritch canon, an invisible stalker, elementals, constructs, are all creatures. 

Where the rubber meets the road? A barbarian wielding a Vicious Warclub will do an extra 2d6 damage to to all the undead hoards, elementals, golems and constructs inside and outside the fortress of the end boss lich. When it comes time to smash through the massive doors (because that's the only way forward), he will not do the extra 2d6 damage. 

If I'm wrong then I've been DM'ing wrong and inadvertently creating house rules. So if I'm wrong, let me know. 

Ok, so this thread was started in 2023, so was about the 2014 rules. However, the 2024 rules do in fact define “creature”. 

From the Rules Glossary:

Creature

Any being in the game, including a player’s character, is a creature. See also “Creature Type.”

Creature Type

Every creature, including every player character, has a tag in the rules that identifies the type of creature it is. Most player characters are of the Humanoid type. These are the game’s creature types:

The types don’t have rules themselves, but some rules in the game affect creatures of certain types in different ways.”

So, essentially, if it has a Creature Type, it’s a Creature.