cirkonstanco

Long, borrowed and entirely predictable, cirkonstanco is one of the words that makes Esperanto easy for anyone with a European language behind them. Spell it carefully though: it is c not s in the middle, and the c is pronounced "ts", so the word starts "tseer-". Like English, it is usually plural in practice, since circumstances rarely come one at a time. Cirkonstanca gives you circumstantial, which is handy for anything legal, and laŭcirkonstance means as circumstances allow.