Which term is associated with creating a sense of tranquility and peace?

The term associated with creating a sense of tranquility and peace is "soporific." This word specifically refers to something that induces sleep or has a calming effect, which inherently contributes to feelings of tranquility and peace. In a broader context, soporific can describe anything that promotes relaxation or a restful state, whether it be atmospheres, sounds, or medications.

In contrast, the other terms do not convey the same calmness or tranquility. "Staunch" generally refers to being loyal or steadfast, which does not relate to feelings of peace. "Spurn" indicates rejection or disdain, creating an opposite effect to tranquility. "Sluggard" describes a person who is habitually lazy or sluggish, which can imply a lack of energy or motivation rather than the serenity associated with tranquility. Therefore, soporific is the term that aligns closely with creating a peaceful atmosphere or condition.