What is "stymies"

Usage examples of "stymies".

But when she looks over the laser-gashed console, she can't figure out how to run the damn thing, and the possibility that she might blow herself up stymies her angry ambition.

The din that prevails at the Bazaar stymies any attempt at serious eavesdropping, but I managed to catch occasional bits and pieces of the conversation as we walked.

When properly exploited, as with a bicycle, it is a stabilizing influence, but when misunderstood, it stymies every effort to—"