quare

Quare is qua re run together, "by which thing", and it splits into two jobs that a reader has to keep apart. In a question it is "why?", interchangeable with cur. At the head of a main clause after an argument it is "and so, therefore, wherefore", the signal that the conclusion has arrived. Cicero uses it constantly in that second way and scholastic Latin uses almost nothing else.

Indirect questions take the subjunctive: nescio quare venerit, not venit. Some editions still print the two words separately as qua re, which is a helpful reminder of where it came from. English "wherefore" is the exact parallel construction and carries the same double life, which is why Juliet is asking why Romeo is a Montague and not where he has got to.