What is the origin of "бо"

Question

I'm curious about the word/ending "бо". For example in the word, ибо, which is basically и + бо with бо meaning потому что, так как итд, а ещё слово "либо" имеет это окончание, но что оно значит? This form seems to match with nothing else in the modern language. In other words it seems completely foreign to me.

Answer 1

Бо is one of a set of particles that go all the way back to Proto-Slavic, and whose ultimate etymology is obscure; most conjunctions in Slavic languages are made of such particles variously spliced together, and many continue to be used on their own as clitics.

Talking about other Slavic languages: curiously, while бо universally means "because"/"for" where it occurs on its own, it's also the common denominator of the words for "or" in Ukrainian (або), Slovak (alebo), and Czech (nebo). And, of course, the Russian либо. How the two meanings are related is anyone's guess.

I can imagine it possibly starting out as a discourse particle similar in meaning to the modern colloquial English "you know", which might explain the divergence into "because" and "or" (think of Don't start trouble with these guys: they don't mess around, you know vs. a car, a truck or, you know, a go-kart), but that's entirely my own speculation.

An interesting, if a bit vague and meandering, book that specifically addresses the somewhat enigmatic origin of such particles (бо, же, ли, etc.), is Непарадигматическая лингвистика: История «блуждающих частиц» by Т.М.Николаева.

Answer 2

Quite obvious либо = ли + бо = or because.

Бо itself is an old preposition which means... well, "because".

Боянъ бо вѣщий,
аще кому хотяше пѣснь творити,
то растѣкашется мысию по древу,
сѣрымъ вълкомъ по земли,
шизымъ орломъ подъ облакы.

Because wise Boyan,
If he wanted to praise someone by a song,
Then he flew as a squirrel on the tree,
As a grey wolf on the land,
As a grey-blue eagle in the clouds.

("The Tale of Igor's Campaign", end of the 12th century, author is unknown)

That's all there's to it ;-)

Answer 3

The word бо retains its own meaning in Polish [bo₁] [bo₂], as a single word:

Бо = потому что = because

   ... не для выигрыша, а так, чтоб только не играть даром, что, по его словам,
                                                           └────┘
                                                            /
                                                           /
     ... nie dla wygranej, byle tylko nie grać za darmo, bo to, jego zdaniem, 
                                                    [Пушкин. Капитанская дочка]

  — А потому, что ветер оттоле потянул, ― отвечал дорожный,
     └───────────┘
       /
  — A bo wiatr pociągnął stamtąd — odparł podróżny,
                                                    [там же]

Polish is interesting at look at in that it retains dozen words, for example, ся = się as a single disconnect-able word for its counterpart in Russian [3], in place of Russian suffix -сь, -ся in verbs:

  Jeśli więc w którymś z późniejszych słowników PWN-owskich łada się znalazła,
                                                                   \
  Даже если в котором в нижеуказанных PWN-овских словарей łada нашлась, 

At the other side, it has concatenation мы in the place of verb, where Russian dropped it [4]:

  znaleźliśmy byli
    _______/
   /
  мы бы нашлись

So, the claim in the beginning is motivated.

Answer 4

The origin is the PIE root bhea̯- "to say" (bhea̯ti = "says"). From the same origin are Russian байка, баять, English fate, fame, fabula etc.