What is the term for assisting someone in committing a crime?

The correct term for assisting someone in committing a crime is "aiding." This concept refers to actively helping or supporting another person in the commission of a criminal act, which makes the person who provides assistance possibly liable for the crime itself. Aiding can include various forms of support, such as providing tools, information, or even encouragement to facilitate the illegal act.

While complicity also relates to being involved in a crime, it broadly encompasses a variety of roles that someone may play in the criminal activity, which may not be strictly limited to active assistance. Conspiracy, on the other hand, refers to an agreement between two or more persons to commit a crime, which does not necessarily imply direct assistance in the execution of that crime. Interference is generally a more generic term that does not specifically connect to criminal activity in this context.

In summary, "aiding" is succinctly defined as the act of providing help or support in the commission of a crime, making it the most accurate choice in the context of the question.