1. verb To startle or surprise someone, as with a piece of information. Tommy totally blind sided me when he told me he was going to prom with my ex-girlfriend.

2. verb To physically strike someone who is not in a position to defend themselves. Come on, ref, isn't that a penalty? He totally blind sided me and hit me in the head!

3. noun The side that one is not currently facing. Come on, ref, isn't that a penalty? He totally hit me on my blind side!

4. noun An area that is not able to be seen, either due to its location outside of the field of vision, or due to some physical obstruction or a defect in one's vision. That car must have been on my blind side because I didn't see it coming at all!