The Collaborative International Dictionary of English v.0.48:

Rei \Rei\ (r?), n.;pl. Reis (r?"?s or r?z). [Pg. real, pl.
   reis. See Real a coin.]
   A portuguese money of account, in value about one tenth of a
   cent. [Spelt also ree.]
   [1913 Webster]

Easton's 1897 Bible Dictionary:

Rei
   friendly, one who maintained true allegiance to king David (1
   Kings 1:8) when Adonijah rebelled.


Hitchcock's Bible Names Dictionary (late 1800's):

Rei, my shepherd; my companion; my friend