The word "irrefutable" usually refers to evidence or personal testimony which is impossible to contradict. Within the legal system, irrefutable proof is what is most likely to convince a judge or a jury, since the opposing claimant or plaintiff will not be able to discredit it. Although this word appears quite often in the English language, its origins are actually from Latin. Most researchers believe that the term "irrefutabilis" first appeared in the Latin language during the early 17th century. Some scholars or linguists, however, will replace "irrefutable" with the word incontrovertible, which can be applied to the same type of unchallengeable evidence. This term was first used in circa 1646.