Which word describes the act of delaying or preventing something from happening?

The word that best describes the act of delaying or preventing something from happening is "hinder." When we say something is hindered, it implies that there is an impediment that slows down progress or makes an action more difficult to carry out. This term captures a sense of actively creating obstacles that make it hard for something to proceed as planned.

While "obstruct" can also suggest preventing something from happening, it often carries a more physical connotation, like blocking a passageway. "Impediment" is closely related, but it usually refers to a specific obstacle rather than the act of hindering over time. On the other hand, "refrain" means to hold back from doing something, which does not accurately reflect the concept of delaying or preventing in a dynamic sense. Thus, "hinder" precisely captures the essence of delaying or preventing something from occurring.