ĉerko

Every language needs this word, and there is no gentle way round it. A ĉerko is a coffin: a wooden box, usually plain, in which a body is buried or cremated. Esperanto handles it plainly. You carry a coffin (porti la ĉerkon), you close it (fermi la ĉerkon), you lower it into the grave (mallevi la ĉerkon en la tombon). None of that is poetic and none of it needs to be.

The words around it. Tombo is the grave, tombejo the cemetery, funebro the mourning, entombigi to bury and funebra ceremonio the funeral service. Ĉerkoportanto is a pallbearer, built exactly as it looks. Ĉerkigi exists and means to place in a coffin, though most writers say meti en la ĉerkon and it reads better.

The etymology is worth a moment, because it is the reason the word looks so unlike its neighbours. French cercueil began as Latin sarcophagus, borrowed from Greek sarkophagos, which literally means flesh-eating. Greek quarries near Assos produced a limestone that was said to consume a body within weeks, and the stone's nickname became the name of the box, then of any stone box, then in French of the wooden one. So ĉerko and sarcophagus are the same word, three thousand years and several sound changes apart, and only one of them still sounds like an accusation.