I looled up my dictionaries.
Kojien and Super nihongo daijiten(CD-ROM) explain Buraku shortly.
But both don't have the word "Burakumin."
Others explain Buraku = villages.

Kojien (Iwanami)
Kokugo Jiten (Kadokawa)
Kanwa Tyu Jiten (Kadokawa)
Shin Kokugo Reikai Jiten (Syogakukan)
Shinsyu Kokugo Kanwa Jiten (Syueisya)
Super nihongo daijiten CD-ROM (Gakkenn)