CrunchGear

Ambidextrous in this context means that it can be used right or left handed with equal ease. Probably because the mouse is symmetrical instead of being one of those mice that form fit into your hand. Now that that’s settled, you are something of a dumbass for not knowing what ambidextrous means, and not looking it up. Don’t be a dumbass.

http://word.sc/ambidextrous: equally skillful with each hand; “an ambidextrous surgeon”

I guess that means that it is usable for both left- and right-handed users.