Definition of "nosebleed"

A haemorrhage from the nose; usually, blood flow exiting the nostrils that originates from the nasal cavity.  examples

(US obsolete slang) A nerd or geek; a dork.

(Philippines, figurative, slang) mental overload (usually attained as a result of having to comprehend new and/or complex concepts or languages that one is not particularly skilled with).

Short for nosebleed seat.  examples