The way humans define words is a powerful way of representing them. In this work, we propose to measure word similarity by comparing the overlap in their definition. This highlights linguistic phenomena that are complementary to the information extracted from standard context-based representation learning techniques. To acquire a large amount of word definitions in a cost-efficient manner, we designed a simple interactive word game, Word Sheriff. As a byproduct of game play, it generates short word sequences that can be used to uniquely identify words. These sequences can not only be used to evaluate the quality of word representations, but it could ultimately give an alternative way of learning them, as it overcomes some of the limitat...