From Japanese-English FreeDict Dictionary ver. 0.1:
[ichi1] [news1] [nf09] 使い, 遣い, [ichi1] [news1] [nf09] つかい
1. (noun (common) (futsuumeishi))
使いにやるerrand, mission, going as envoy
2. messenger, bearer, errand boy, errand girl
3. 使い魔familiar spirit
4. (noun, used as a suffix)
(noun, used as a prefix)
魔法使い (often read as づかい when used as a suffix)
use, usage, user, trainer, tamer, charmer