An astronomical unit of mass. Units are so massive, that most, if not all things are measured in Micro Masons (MMason).
VY Canis Majoris, the largest known star has a mass of 0.5 Mason.

Betelgeuse, on the other hand, has a mass of 0.1 Mason
by Barbecued Ribs April 15, 2010
Get the Mason mug.
A very quiet, but cool girl. Usually with dark hair and certain eyes. She always looks mad, but in actuallity, is usually in a good mood, and only looks pissed because she is in deep thought. She'll have a decent body, and face, but she makes up for that with her wicked sense of humor. When you see her around with other guys, you'll get extremely jealous. If you ever hear a high-pitched laugh, a deep voice, or a very loud yell, you'll know it's a Mason. Voices her sexual tensions about a lot of guys, but when she likes a guy, she's the sweetest girl you'll ever have, if you ever get a Mason, dont let her go. And if she ever asks you out, you'd be a fool to say no.
"Look at that girl, she is such a Mason."

Friend "Who was that girl that talked about blowjobs in science today?"

"Oh, that was Mason, but she was just jokeing."

"Who was that guy you were talking to earlier today?"
"... Um, that was Mason, and she's a girl..."

"You're so lucky, you have the sweetest girlfriend ever."
"I know, she is such a Mason".
by Tangy bear February 28, 2012
Get the Mason mug.
Mason is one of the most althletic kids you will ever meet. He is definitely a keeper and you shouldn't break up with him. He likes Viedo games, likes to hang out with his friends, and loves to play a lot of sports. A Mason is very energetic and is super cute. He has amazing hair and almost always has a six pack.
Wow he is good at hitting a baseball. He is such a Mason
by M and M12345 January 11, 2017
Get the Mason mug.
When u go to High School You find the ugliest year 10 and start dating her so u can brag to your friends that you have a girlfriend and be a simp.
The Mason is when You are new to High School and you want a Girlfriend so you find the worst year 10 and date her so you can brag to your friends and be a simp.
by deez almonds 420 March 26, 2021
Get the The mason mug.
Mason is a guy who you think is an utter asshole at first, but after about a month of dealing with him, he starts to grow on you. He’s the kind of person to send you an extremely worrying meme that he found on Reddit at 4 in the morning. He’s not much for being emotionally vulnerable or showing how he truly feels, unless it’s in a very specific meme. If you try to be vulnerable with him he’s either going to laugh or awkwardly make a terrible joke about your extreme trauma. Gotta love the dude tho.
Mason has over 1,000 memes on his cellphone.
by Richie <3 February 17, 2022
Get the Mason mug.
Someone who builds things up only to knock them down at a later time.
After Toby put down the girl he was talking to, I was ready to knock that Mason clean out.

My son always destroys his lego, he's going to be a Mason real soon.
by The Man with the Golden Gun January 13, 2013
Get the A Mason mug.