Which of the following best describes metaphor?

A metaphor is a figure of speech that directly implies a comparison between two unrelated subjects without using connecting words such as "like" or "as," which are characteristic of similes. It suggests that one thing is another, providing a deeper understanding or insight by highlighting similarities between the two. For instance, saying "time is a thief" implies that time steals moments from our lives, giving us a vivid image of how fleeting time can be. This use of language allows writers to convey complex ideas or emotions in a more relatable way.

The other descriptions do not accurately capture the essence of a metaphor. While a direct statement about a subject suggests clarity, it lacks the implicit complexity that metaphors provide. Comparisons made with "like" or "as" signify similes, not metaphors. Lastly, a narrative device that creates suspense pertains more to storytelling techniques rather than a specific form of figurative language. Thus, the characterization of metaphor as an implicit comparison aligns precisely with its function and usage in literature.