With Christianization in the year 1000, many more foreign words (from the international language of the church) were introduced into the language and the Icelandic vocabulary was substantially increased. Examples of words from this time are: “prestur” (priest), “kirkja” (church), “biskup” (bishop). A considerable number of personal names were added to the vocabulary (i.e. of Christian origin). As a result of the influence of foreign literature during the middle ages, words such as “kurteis” (courteous), “kurteisi” (courtecy), and “riddari” (knight, rider) were introduced.
From around time of the Reformation (1550) until late into the nineteenth-century, Icelandic relations with foreign nations were to a considerable degree confined to those with the Danish. As a result, Icelandic was affected by Danish. A lot of church material was translated out of Danish and German, the highest level of government was in the hands of the Danish, as was trade. This all had a part in the increasing Danish influence on the Icelandic language. A Danish linguist, Rasmus Christian Rask, who came to Iceland in the year 1813 considered the language so strongly influenced by Danish that he thought that if nothing was done barely anyone would understand Icelandic in 100-200 years.
But while the language came to be shot with Danish during this period, the greatest part of the vocabulary held together unchanged. This was because there was little change in work patterns and the fact that Old Icelandic literature and poetry was constantly alive amongst the Icelandic people.