In the middle of Lent, most Christians tend to think about the importance of fasting but only few seem to remember how important alms are. Alms is a word that does not appear in the Old Testament, but it is used quite a few times in the New Testament: "σοῦ δὲ ποιοῦντος ἐλεημοσύνην μὴ γνώτω ἡ ἀριστερά σου τί ποιεῖ ἡ δεξιά σου" or in English "But when you give alms, let not your left hand know what your right hand does" (Matthew 6:1) is one of the most important verses where the word appears. That is, actually, where the adventure of the word begins as biblical translators carried it westwards.
For lack of a better alternative, St. Jerome (Eusebius Sophronius Hieronymus), who was commissioned by Pope Damasus I in 382 AD to make a revision of the old Latin translations of the Bible, decided to keep the word as is and simply transliterate it into Latin. So, the word appears in the Vulgate, the traditional Latin translation of the Bible used by the Roman Catholic Church, in a form that is almost identical with the original Greek word: "te autem faciente elemosynam nesciat sinistra tua quid faciat dextera tua".
However, Latin was spoken widely across Europe in the early Middle Ages and linguists theorize that, at some point, the word changed its form into alemosyna and then into alemosna in Proto-Germanic. That is where the Anglo-Saxons picked it up and transformed it into ælmesse (West Saxon dialect, 990 AD): "Soðlice þonne þu þíne ælmessan dó. nyte þín wynstre hwæt dó þin swyðre". As Old English evolved into Middle English in the late Middle Ages, ælmesse changed once more to become almes in the Wycliffe Bible (1395): "But whanne thou doist almes, knowe not thi left hond what thi riyt hond doith". The word, finally, settled into its modern form in King James Bible (1611): "But when thou doest alms, let not thy left hand know what thy right hand doeth".
It was quite a long adventure for such a small word!