The Collaborative International Dictionary of English v.0.48:

Ressaldar \Res"sal*dar\, n. [Hind. ris[=a]ld[=a]r, fr.
   ris[=a]lt[=a]troop of horse + Per. d[=a]r holding.] (Mil.)
   In the Anglo-Indian army, a native commander of a ressala.
   [Webster 1913 Suppl.]