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1.
Verb: To look at a girl's tits and guess what cup size she is

Noun: A guess of a girl's cup size
Person 1: Dude her tits are huge!

Person 2: I know right! I think she's a C cup, but that's just a breastimate
by CammyCakes999 July 13, 2012
 
2.
The technique used by bra-fitters and corsetiers to approximate breast size and therefore bra size. Often men and women can learn this technique for their own common use.
Customer: Hi there, I would like a bra fitting please

Jennifer: OK, well I breastimate you are a 10/32C so lets start there shall we?

OR

Daniel: Woah look at her GIANT breasts!

Beth: Sorry man, shes just wearing the wrong bra and theyre hanging out. I breastimate she's only a 14/34 C.
by Beffeh January 18, 2011