It's getting to the roots that always fascinates me. Bous in Greek is apparently a cow (hence also bovine) and kolos something like to cultivate; a boukolos is someone who 'cultivates' cows: a cowherd.
entomology of the word is Jewish. Kind of not well known unless you're more familiar with the culture. Similar to the Jewish cultural word, 'schmekel' . Decades ago I was at a giant state funded wedding for a couple in Mexico City that were mostly jewish. At our table I asked what that word meant and it didn't seem to be too traumatic to anyone that I had asked