A free, open-source, decentralized social network. Anyone can create or join an "instance" of Mastodon, where an instance is a unique domain name, and instances can be "federated" with each other so someone using one instance can interact with users on another instance. Comparable to email, where a Gmail user can email with a Yahoo mail user and vice versa. Comparable to Twitter, but less corporate and fewer Nazis. However, admins can run their instances however they wish, and may choose to allow/prohibit/monitor content that includes racism and other -isms, pornography, violence, etc.

The service allows posts to be placed behind a content warning (CW), and allows media to be marked as NSFW, and can be posted publicly, to followers only, as a direct message, or unlisted (where the post is public, but does not show in the federated timeline). Most instances allow posts to contain 500 characters available, and some instances allow much longer posts.

Posts are called "toots," and reposts are called "boosts," but instances can be customized to fit a theme or other preferences. Usernames are formatted as @username@instance.domain, such as @gargron@mastodon.social, where user @gargon is on the instance mastodon.social.
After I joined Mastodon, I deleted my Twitter account and never looked back.
by nothin2seehere June 3, 2017
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A four-piece metal band from Atlanta.
The grestest metal band of the last 10 years, Mastodon have released two full length albums and one EP.

Lifesblood (EP, 2001 Relapse)
Remission (LP, 2002 Relapse)
Leviathan (LP, 2004 Relapse)

They own your fucking soul.
"I hope Mastodon play Elephant Man tonight"
by sugna November 23, 2004
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Adjective used to describe a huge, gigantic penis. Named after the mastodons, an extint species of elephants.

Synonym: elephant cock
I'm going to rape you with my mastodonic 300-mile long cock.
by Roth Vantage January 5, 2015
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When the girl is on all 4 and you ram your dick from across the bedroom, like an elephant taking down a tree while your girl cries like an elephant calling for help
I made my girl come to my house i flipped her over and she was on her 4, so I mastodon her, such a great experience.
by JKM23 November 19, 2017
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The new kings of the heavy metal world. They are a prog-sludge metal fusion, with their earlier releases leaning towards sludge metal and their later releases leaning towards a prog-sludge fusion.

Their 2004 albumn Leviathan is a classic record and their 2006 albumn Blood Mountain launched them into the mainstream. They have a new albumn, Crack the Skye, coming out Spring 2009.

All of their albums center around a different element and story 9with the exception of Remission, which loosely focuses on fire). Remission is fire, Leviathan is water, Blood Mountain is earth, and Crack the Skye focuses on aether.

Remission (2002)
Leviathan (2004)
Blood Mountain (2006)
Crack the Skye (2009)
Mastodon are the new knigs of the metal world.
by ghdhlgh5796h January 30, 2009
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mastodon is, besides an extinct mammal and a metal band, a decentralized open-source social media tool. If I'm understanding it correctly, there are a lot of different servers running mastodon software. These are called instances. People with accounts on one instance can interact with people on other instances. All these instances together are called a federation. It seems to be particulary popular with people who are fed up with twitter, because of it's lack of ads and increased discourse between people running the instances and people using it. It also seems to be popular among japanese people, for two of the biggest instances are japanese language, one of which is hosted by pixiv.
It is also possible to host a private mastodon instance that is invisible to outsiders. This could prove very helpful for companies.

OFFICIAL WEBSITE: joinmastodon DOT org
POPULAR INSTANCE: mastodon DOT social
VIDEO EXPLANATION (OFFICIAL): youtu DOT be/IPSbNdBmWKE
hey have you heard of mastodon? You can easily find your twitter mutuals if they've connected their accounts.
by I like mastodon August 21, 2018
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Used to proclaim oneself as being totally manly, usually after having performed an amazing feat.
"Did you see that goal, I'm a total mastodon!!"
by Junkyard Dog July 1, 2004
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