Boila

Boila (Bulgarian: боила or Bulgarian: боил; Old Church Slavonic: бъɪля; Greek: βοιλα) was a title worn by some of the Bulgar aristocrats (mostly of regional governors and noble warriors) in First Bulgarian Empire (681-1018). For the linguists, the title "Boila" is predecessor or old form of the title "Bolyar".

The Boil(a)s were two types: internal ("great") and external ("small"). The internal Boilas were governors of the Comitates (administrative regions).

Most of the popular linguists says that "Boila" has old-Turkic or old-Iranian origin and the meaning of the word can be translated as "noble".

...
Wikipedia