"full of feeling," 1860, from soul (n.1) + -ful. Meaning "expressive of characteristic Black feeling" is from 1964 (see soul (n.2)). Earlier as a noun (1640s), "as much as a soul can hold."
soulful eyes
soulful music
souffre-douleur
sough
sought
souk
soul
soulful
soulless
soulmate
sound
Soundex
soundless