←
Old Church Slavonic сꙑнъ (inherited)
←
Old Church Slavonic син҄ь (inherited)
←
Proto-Balto-Slavic *sū́ˀnus (inherited)
←
Proto-Indo-European *suHnús (inherited)
←
Proto-Slavic *synъ (inherited)
←
Proto-Slavic *siňь (inherited)
→
Bulgarian синьо (affix)
→
Bulgarian синьо (affix)