from Latin testimonium "evidence, proof, witness, attestation," from testis "a witness, one who attests" (see testament) + -monium, suffix signifying action, state, condition.

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noun (plural testimonies)

a formal written or spoken statement, especially one given in a court of law.

(特に法廷での宣誓)証言; 供述, 陳述書

evidence or proof provided by the existence or appearance of something:

〖単数形で〗 «…の/…という» 証拠, 証明 «to, of/that節»

e.g. his blackened finger was testimony to the fact that he had played in pain.

a public recounting of a religious conversion or experience.

｟古｠ (信仰などの)公表, 公式宣言, 表明.

archaic a solemn protest or declaration.

Middle English: from Latin testimonium, from testis ‘a witness’.