Here are some synonyms for "wistful":
* Yearning
* Nostalgic
* Regretful
* Melancholy
* Pining
Examples of how "wistful" is used:
* "She gave him a wistful smile, remembering the days they had spent together." This implies a longing for the past and a sadness that those days are over.
* "He gazed at the old photograph with a wistful expression." This indicates a longing for the people and times captured in the picture, likely a feeling of nostalgia.
* "The melody filled the air with a wistful sweetness." This suggests a melancholic and longing quality to the music.
In essence, "wistful" implies a bittersweet emotion, a yearning for something that is not present and likely cannot be recaptured.