testamento

One word, two worlds, and Esperanto keeps both. The legal sense is primary: a testamento is the document in which you say who gets what. The religious sense is the Old and New Testaments. English does the same double duty and so does almost every European language, which is convenient and also slightly misleading, because the second sense got there by an accident of translation.

The accident, in one paragraph. The Greek New Testament calls the relationship between God and his people a diathēkē, a covenant. Latin had a perfectly good word for covenant, foedus, and the Vulgate did not use it: diathēkē also covers a testamentary disposition, and Latin testamentum was chosen. Every Western translation inherited the choice. So English says Testament, and Esperanto says Testamento, where Covenant would be nearer the Greek. The personal names article deals with the knock-on problem of what to call the people inside la Malnova Testamento once you are writing in Esperanto.

The root is a witness. Testis is a witness standing by, and the family it threw off is large: testify, testimony, attest, protest, contest, detest. In Esperanto the visible relative is atesti, to bear witness, at rank 1404, and atestanto, a witness. A will works because it is witnessed, and the word admits as much.

A false seam in the same tier. Testudo, a tortoise, sits at rank 2611 and shares five letters with this word. It is not related. Testudo is Latin testa, an earthenware pot or a shell, named for the animal's armour; testamento is Latin testis, a witness. Two different Latin words that happen to start the same way, and nothing in a tortoise has ever given evidence.