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1) In special relativity, the proper length of an object moving at velocity close to that of the speed of light is its length as measured by an observer in the rest frame of the object.

2) A massive shit.
1) Will: Dude, that 30cm ruler travelling at the speed of light looks to be only about 28.5cm.
Nathaniel: Yeah, that's because it's proper lenth is 30cm.

2) Nathaniel: Dude, I just crimped out a proper length.
Will: Yeah, thats a proper brown length.
by justabusta January 22, 2011
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Jul 25 Word of the Day
A jack off buddy (from 'cum' /'come', meaning 'semen', and 'companion'); a friend that you get together with for sessions of solo or mutual masturbation
Variant of: cumpanion (from 'companion' & 'cum'); jack off buddy & wank bud & JO buddy
Similar to: fuck buddy
My bf and I used to really get it on together, but now it's just the occasional cumpadre wank
by Gladys Pipps-Knightley May 14, 2007
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