The word used when the speaker is unable to find the correct term.
I am supposed to um... use this word in a sentence.
by Elizabeth Grey July 9, 2016
sound which verbally comes out the mouth. the other variation is uh and they both mean nothing
by Lukasucksatdefinitions May 4, 2020
More recently used to unintentionally irritate people who prefer straight forward answers. Literally, "something is urgently wrong but instead of me just immediately telling you, you must figure it out yourself in the amount of time it takes me to make this sarcastic and unhelpful remark."

Can be typed as well.
Example, this used to be proper protocol in an urgent situation--
Bob: "Joe, watch out for that large pothole you seem to be unknowingly driving into."
Joe: (avoiding pothole) “Thank you for your timely and straight-forward warning. I appreciate you using the first sentence after you were alerted to this danger to tell me about this pothole, instead of uttering a one-worded, useless phrase.”

Modern protocol, same situation--
Bob: (sarcastically) "Um..." Joe: “What?..... What?” (car drives into pothole)
Bob: “Wow, good job.”
by Jake Gus December 1, 2004
one of the 2 most commonly used words in the english language (the other is uh)

usually it means that the speaker is searching for an idea (or at least thats usually when i use it)
reporter: y is the segway too redundant?

dean kamen: um...that is...um well...
by unusu-al December 7, 2003
a word used as a filler in a sentence. mainly used by blondes in a situation when they have nothing else to say
brunet: THE HOUSE IS ON FIRE!!!!
blonde: UM...WHAT DO WE DO?
by me silly! April 26, 2011
In conversation, a word that announces one's contempt for and hostility toward the person they're about to contradict. Most common on the Internet, for obvious reasons.
Person 1: The first movie I ever saw in the theater was "Empire Strikes Back." Man, that was intense for a 6-year-old, so much larger than life. And when Darth Vader said "Luke, I am your father," I was freaking out. I'll never forget that day.

Person 2: Um, Vader never said that line.
by burn_x_freeze May 16, 2009
A word used when speaking and uncertain of another word. Used to stall for time to think of a new word if you're dumb.
I, think you are really, um... unique?
by Romagi April 19, 2003