Which word describes someone who is lacking spirit, interest, or liveliness?

The term that best describes someone who is lacking spirit, interest, or liveliness is "lackadaisical." This word specifically captures a sense of indifference or a sluggish attitude towards tasks and responsibilities, often conveying a lack of enthusiasm or energy. A lackadaisical person might approach situations with a careless or half-hearted attitude, demonstrating an absence of motivation or engagement.

In contrast, the other choices do not fit this definition. "Indifferent" suggests a lack of concern or interest but does not inherently imply a lack of liveliness. "Insecure" refers to feelings of uncertainty or lack of confidence, which is unrelated to the concept of spirit or liveliness. "Invigorated" describes a state of energy and enthusiasm, the opposite of what is meant by lacking spirit or liveliness. Hence, "lackadaisical" stands out as the most accurate term for this description.