Learn English – word that means ‘boring to death’

What is your problem with condolence? It does not only apply to grief of death, but of any severe suffering. Its origins are similar to sympathy and compassion, all meaning essentially to suffer together (or as the commenter said "I feel your pain.")

However, all three of these words seem to work: I offer my sympathies, or condolences. I'd also say that to say "I'm sorry" only means "I apologize" in some circumstances. "I'm sorry for the terrible thing happening to you" does not in any way imply that you feel responsible, or are accepting any blame.

Per Google, bifortnightly and bi-fortnightly together have been used about 5000 times on the web, frequently as objects of ridicule rather than as serious terms for "four-week-ly", occasionally as examples of misunderstanding of whether bi is a multiplier or a divider.

Although the lunar cycle is often thought of as 28 days, lunarly doesn't actually work to indicate 28 days, because the moon's sidereal period is only 27.3 days.

Regarding quadweekly and quadriweekly, I like quatriweekly or quatri-weekly better. Quadroon and quadrant, for example, use quadr- as one-fourth, while quatrain uses quatr- as four; but the roots of all of them are closely related to words meaning four.