l0s3r Share definition Flag Someone really pathetic. They want to be l33t but even l33t losers consider them to be a loser. The most pathetic form of life. Get out l0s3r before we h4x0r your c0mp00ter. l0s3r by w00tw00t April 5, 2003 0 0 Get merch Get the l0s3r mug. Buy Now — $32.95 See more merch