A feeling of longing for the past can best be described as what?

The term that best describes a feeling of longing for the past is "nostalgia." Nostalgia encapsulates the emotional response individuals experience when they reflect fondly on past events, memories, or experiences. It often brings about a sense of warmth and yearning for times gone by, whether those memories are from one’s childhood or significant life events.

The other terms do not convey this specific sentiment. "Impetus" refers to a driving force that propels action or momentum. "Quintessence" denotes the most perfect or typical example of a quality or class, while "meticulousness" highlights the quality of being very careful and precise, particularly in attention to detail. None of these captures the essence of longing or a wistful remembrance of the past like nostalgia does.