What a pity! In Lingo, I claimed that “English has no loanwords from Bulgarian, with the debatable exception of the name of the Bulgarian currency, the lev, which literally means ‘lion’.”
I’ve just discovered that I missed one, and a very colourful one too: bugger. The invaluable Online Etymological Dictionary has this to say about it (I’ve edited the entry for clarity):
Bugger Meaning: ‘sodomite’, earlier ‘heretic’. First attested in 1550s. Derived from Mediaeval Latin Bulgarus, meaning ‘Bulgarian’. So called from bigoted notions of the sex lives of Eastern Orthodox Christians or of the sect of heretics that was prominent there in the 11th century. Compare the Old French word bougre for ‘Bulgarian’, also ‘heretic, sodomite’.
So it was either sex life or sect life among the Bulgari, as perceived by Western European Catholics, that gave us bugger. And of course Bulgarus was merely the Latinised form of the word used by the Slavic people in question. They in turn had borrowed it from a Turkic language, spoken by their erstwhile Turkic overlords. Its original meaning seems to have been either ‘mixed (group)’ or ‘disturbers’.