From Japanese-English FreeDict Dictionary ver. 0.1:
[ichi1] [news1] [nf04] 弟, [ichi1] [news1] [nf04] おとうと, おと, (word containing irregular kana usage) おとと, てい
1. (noun (common) (futsuumeishi))
Note: humble (kenjougo) languageyounger brother, little brother, kid brother
2. (てい)
Note: archaismpupil, apprentice