quārē (not comparable)
- (interrogative) by what means, how
- (relative) by which means, whereby
- (interrogative) from what cause, on what account, why, wherefore
Odi et amo, quare id faciam, fortasse requiris; nescio, sed fieri sentio et excrucior. 
- I hate and I love. Why I do this perhaps you ask. I do not know, but I sense that it happens and I am tormented.
- (relative) therefore, and so, hence, for this reason
Inveniuntur enim praeter amnem mirae villae et horti, qui a regibus Franciae in XVI° saeculo structi sunt: quare Liger hodie saepe regale flumen vocatur. 
- However, besides rivers/streams are found marvelous estates and gardens, which were constructed by kings of France during the 16th century: which is why the Loire today is often called a royal river.
Quare quassato corpore neque frigora neque aestus facile tolerabat. 
- Hence, because of his delicate health, he could easily tolerate neither cold nor hot conditions.