Etymology is the science which seeks the origin of words. It is a scientific discipline since the middle of the 19th c. What is needful to make an etymological proposition? Well, a good etymology complies with two conditions.
First condition: the etymologist has taken the form history of the word in question into consideration. Example: in the Middle Ages, the English word land was pronounced lond; an etymologist ignoring this is unable to give a correct etymological explanation, of course, for he 'll conclude that land is a relatively modern word. The French word dame in the game name jeu de dames, board game specialists assume, derives from the French word dame = 'chess queen'. They base their case on the first recorded forms. But are these forms really the oldest ones? Because of this lack of investigation the current etymology of the game name jeu de dames is unreliable.
Another example of an easy etymological proposition was launched by the Frenchman Jean-Michel Mehl [1990:147]. In his opinion, dames = 'draughts' could go back to the German word Damm or the English word dam, both meaning 'fortress, rampart'. The strategy of the game is to break through to have a piece promoted and at the same time to prevent your opponent to do this by building a fortress. However, Mehl does not explain how the French game name dames was originally pronounced, nor how a French game name can go back to a German or English word. Or did Mehl assume that the French game name jeu de dames was borrowed from German or English?
Second condition: the etymologist has explained the sense development of the word in question in a satisfactory manner. What we call a "new word" mostly is a new sense of an existing word; a word underwent an extension of meaning. It stands for reason that this "old" and "new" word have many semantic similarities.
In all likelihood, French dames = 'draughts' is an extension of meaning [Stoep 2005:74]. Let us suppose the French have always pronounced this word in the same way. The first reference of dames = 'draughts' in a French text dates from 1508. The etymologist's task is to trace how many words dame occur in the French vocabulary of the early 16th c. He notes dame = 'woman of rank' and dame = 'chess queen', and will opt for the second dame. Of course, for chess and draughts are both board games, are both played on a chequered board and share the rule of promotion. To make quite certain, he could make an inquiry into the sections of the population which played draughts about 1500: are there indications that the women of the higher classes had a great liking for draughts? If he finds them, he must choose between dame = 'womand of rank' and dame = 'chess queen'.An example of a semantically unsatisfactory etymology is the generally accepted explanation of the Spanish word dama = 'chess queen', which was borrowed by French chess players as dame. In medieval chess, the literal meaning of the piece next to the king was "queen". A nice name for a weak piece. In Spain in the 15th c. chess was reformed. The chess queen was given much more power and became the most powerful piece on the board. But chess historians are faced with a problem: the name of this mighty piece was Spanish dama. This word was a new sense of the Spanish word dama = 'woman of rank', historians assume. But how to explain the change of name? The old weak piece was called "queen"; why acquired the new powerful piece a name which only meant "woman of rank"? Click for this problem here.