Myopia means short-sighted, particularly with respect to planning -- neglecting long-term consequences in favor of the short term. The extreme case, in which only immediate rewards are considered, is of particular interest. We can think of a myopic agent as one that only considers how best to answer the single question that you give to it rather than considering any sort of long-term consequences. Such an agent might have a number of desirable safety properties, such as a lack of instrumental incentives.