1. Deep in sad thoughts; especially, thoughts of something yearned for or lost, or expressing this sad yearning: Shirley had wistful memories when she thought about the times when she was growing up on her father's farm.
2. Full of wishful yearning; pensively sad; melancholy: The wistful music filled Mike with sadness.
3. Etymology: the meaning of "longing, yearning" existed in 1613-1616; formed from obsolete English wist(ly), "intently"; which was of uncertain origin before 1500.

The meaning of "expectantly" or "yearningly eager, longing" was first recorded in 1714.