Which word can best be defined as "artifice"?

The term "artifice" refers to a clever or cunning device or expedient, especially one used to trick or deceive others. In this context, the word "ruse" aligns perfectly with this definition, as it signifies a deceptive maneuver designed to mislead or trick someone.

Ruses are often employed in various scenarios where ingenuity or craftiness is necessary to achieve a particular aim, particularly in contexts involving strategies or tactics. This relationship illustrates how both terms encompass themes of deception and cleverness.

The other words do not carry the same meaning. "Banish" refers to expelling someone from a place, "motivate" is about providing someone with a reason to act in a certain way, and "sporadic" describes something occurring at irregular intervals. None of these relate to the notion of cunning; hence they do not fit with "artifice" as accurately as "ruse" does.