Which word refers to the action of turning aside or steering off course?

The action of turning aside or steering off course is best captured by the word "veer." This term specifically denotes a sudden change in direction, which aligns perfectly with the question's context regarding steering off course.

While "divert" might seem relevant since it also implies a change in direction or course, it carries a connotation of redirecting something from its intended purpose or path, which can differ slightly from the notion of a sudden or inadvertent turn indicated by "veer."

The term "venture" implies taking a risk or attempting something new, which does not relate to the concept of changing direction. Hence, "veer" is the most precise choice for describing the action of turning aside or steering off course.