A Cinematic Universe is the whole Filmography for a certain brand, company etc.

The DreamWorks universe for example,

The most popular DreamWorks movies are Shrek, Puss in Boots, Kung-Fu Panda, Madagascar etc.

The Shrek part of the DreamWorks Cinematic Universe would contain all Shrek movies, the full character list (background characters included), and the timeline.

The same would go for the other movies. Timeline is less important for one specific movie (we don't need to have everything written down, some things that happen won't be important to the story at all, and aren't important to the timeline), but the order of the movies is more important. The example down below shows the difference.

Example:

Shrek is a disgusting swamp monster, he has a simple life and is a simple swamp monster .. (the other parts of the movie written out.) ❌
(Too much information, practically a spoiler.)

Shrek is a swamp monster who saves, falls in love with, and marries a princess with a Donkey by his side. ✅

(Short, literal summary of the first Shrek movie.)

An example how it would be used in a conversation is down below. (DreamWorks themed.)
“Do you know about the DWCU?”
“What's the DWCU?”
“The DreamWorks Cinematic Universe is all of the media and the characters involved.”
...
“Remember when Shrek and Fiona had sex on the beach?”
by Simple man simple life January 31, 2023
Get the Cinematic Universe mug.
The Marvel Cinematic Universe (MCU) is an American media franchise and shared fictional universe that is centered on a series of superhero films, independently produced by Marvel Studios and based on characters that appear in publications by Marvel Comics. The franchise has expanded to include comic books, short films, and a television series. The shared universe, much like the original Marvel Universe in comic books, was established by crossing over common plot elements, settings, cast, and characters. Clark Gregg has appeared the most in the franchise, portraying Phil Coulson, an original character to the MCU.

The first film released in the MCU was Iron Man (2008), which began the first phase of films, culminating in Marvel's The Avengers (2012). Phase Two began with Iron Man 3 (2013), and is expected to conclude with Avengers: Age of Ultron (2015). Marvel is also preparing Phase Three, beginning with the release of Ant-Man (2015). The universe began to expand with the release of the first official tie-in comics in 2010, and saw further expansion with the Marvel One-Shots direct-to-video short films in 2011 and the TV series Marvel's Agents of S.H.I.E.L.D. in the 2013–14 season. Marvel has multiple films and television projects in various stages of development.

The franchise as a whole ranks as the second highest-grossing film franchise of all time and has inspired other film studios with comic book character film rights to attempt to create similar shared universes.
The following film scene, from Iron Man (2008), is an example of the Marvel Cinematic Universe in action:

after end credits
Tony Stark: arriving home Evening, JARVIS!
Jarvis: voice distorted Welcome home, sir...
Stark stops as he sees a figure in his living room
Nick Fury: "I am Iron Man". You think you're the only superhero in the world? Mr. Stark, you've become part of a bigger universe. You just don't know it yet.
Tony Stark: Who the hell are you?
Nick Fury: Nick Fury. Director of SHIELD.
Tony Stark: Ah.
Nick Fury: I'm here to talk to you about the Avenger Initiative.
by The Centurion October 6, 2014
Get the Marvel Cinematic Universe mug.
When you are watching a porno and it references another porn video you have watched
Bro I have seen all of The Porn Cinematic Universe I think this makes me a virgin again
by Tim The Wise June 12, 2021
Get the The Porn Cinematic Universe mug.
It’s a universe where earth code named Earth-199999 and has a country called sokovia
Breaking news, the avengers fucked up sokovia in the marvel cinematic universe
by Some1 @ the internet July 17, 2021
Get the Marvel cinematic universe mug.
Quite possibly the dumbest, and greatest, cinematic universe since Marvel
"Did you see the Ace Cinematic Universe got a new character?"

"NOT ANOTHER ONE"
by AceBanned February 1, 2022
Get the Ace Cinematic Universe mug.
A Fictional Universe made by people who call themselves "Foomers". It is much similar to our own universe except that it's populated with railroad companies that do not exist. The requirement to join said universe is to become a "foomer" and have a fictional railroad that makes sense and isn't a complete meme.
Man 1: Be careful while traveling, lets pray you end up somewhere nice like the Hope Arkansas Cinematic Universe.

Man 2: Sure bets the Auto Train Dismesion
by Angery Masshole August 31, 2021
Get the Hope Arkansas Cinematic Universe mug.