Skip to main content
Urban Dictionary Merch
Your favorite words on things you can wear, drink from, read, or give to a friend.
The Urban Dictionary Store sells gifts you’ll have to explain.
Mean Time Between Failure
Way to quantify the performance of a machine or part.
MTBF = (Total Time of all Parts run) / (Total number of failures)
Good if all parts fail.
Bad if very few of the parts fail. It is very deceptive in this case.
A hypothetical machine generally runs between 60 and 100 hours before failing.

If you run 3 of them for a total of 240 hours, and all 3 fail, you have a MTBF of 80 hours per failure. Makes sense.

If you run 100 of them in an application where the job is complete after 50 hours, at which point you don't run it again, it is possible that only 10 or so will fail. MTBF could be about (90*50 + 10*25) / (10) = 475 hours per failure. This is insane, since you would be lucky if a single tool made it to 200 hours or continuous operation.
MTBF by guided fox July 7, 2006
Related Words
Mean Time Between Fucks (cfr. Mean Time Between Failure in IT)
How is your MTBF lately ?
MTBF by Pat___ January 9, 2008
mean time between failures. it is used to measure the reliability of machines or systems. It is the result of dividing the total work time planned by the number of stoppages due to equipment failure.
In the american automobile plants mtbf has been found to be just 30% of that at the japanese makers, even in the US, like honda and toyota
mtbf by Enrique Mora February 20, 2004
1. In machines, the amount of time, when operating a bank of machines, between any one of them failing. Not lifetime, as hard drive manufacturers want you to think. It is the average amount of time between failures of indivdual parts when talking about a system.

2. In biology, the average lifespan of each individual organism which has a particular set of genes or "environment of luck". An "environment of luck" can be something like all people who fly on a plane, living around individuals who want you dead in the worst way,all people who smoke, or some other demographic.
1. When punching laced cards on a bank of keypunch punched-card makers, the average MTBF is about three cards.
1. In an average house, it is normal to burn out 3 incandescent light bulbs in a month. Therfore the MTBF is 10 days.
2. Teacher:"King tut only lived to be 19."
Mocking Student:"Wow, his MTBF is in the toilet!"
2. "The MTBF of John Benet Ramsey is quite short."
Meantime between Fornications
Hmmm... I wonder what that chick's MTBF is....
MTBF by hudsonsculler@hotmail.com January 16, 2005
Sarah: ugh becky I'm on my period
Becky: same! we're MTFL!!
mtfl by heyayall October 16, 2018
More from Urban Dictionary

trucker's tan 

A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.
I had a trucker's tan after driving for 10 straight hours on a sunny day.
Word of the Day on October 5, 2026
The phenomenon where adults salivate at children's toys
Every time I walk into the toy aisle, I catch myself kidulting over the latest action figures and LEGO sets!
kidulting by Emotional Cruiser October 12, 2025
Word of the Day on October 4, 2026
British slang for a scientist or technical expert, esp . when the speaker is not certain of the expert’s specific field of study. Not necessarily derogatory, but typically used by persons without a technical background. In the US, the equivalent would be “egghead”, “squint”, or “geek.”

Origin of the word is unknown. Started sometime in World War 2. Given the typical evolution of British slang, could easily have started because what these experts did was confusing or “baffling” to the common person.
According to the boffins downstairs, the murderer used a serrated blade.
Boffin by Agnon February 11, 2023
Word of the Day on October 3, 2026

Pee Calculus

When you have to pee in a movie but don’t want to miss anything, and must do the following mental equation: will the amount I have to pee cause enough discomfort to diminish my attention capacity for the remainder of the movie to an extent which is greater than the amount of the movie I would miss by making a mad dash to the restroom.
I saw Satantango last night, wonderful film but by the 5th hour I had to start doing pee calculus.
Pee Calculus by anorlondo October 1, 2026
Word of the Day on October 2, 2026
Literally "dirty" pronounced with a West Indian accent. Can also have a positive connotation, for example Sean Paul's album title "Dutty Rock".
"The girl is pretty but she corrupt and dutty!"

or, in a positive usage:

"Booya! That freestyle was dutty!"
Dutty by J Hall April 3, 2003
Word of the Day on October 1, 2026
korean word for madam, older woman
Ajumma wait a moment
Ajumma by aintnotinbutnice July 5, 2009
Word of the Day on September 30, 2026
Load more