The winner of the 2009 Dutch Word of the Year, as selected in an online poll conducted by the Van Dale dictionary group and Pers newspaper, was ontvrienden, a social networking verb equivalent to English unfriend or defriend. NRC Handelsblad recently reported that ontvrienden can be found in the Dutch historical dictionary Woordenboek der Nederlandsche Taal with citations back to 1626:
The entry quotes references dating from 1626 and 1658. One is a reference to the infamous courtesan of Lais, a woman so beautiful — and sexually available — that she drew pupils away from a famous philosopher, "defriending" him in the old-fashioned sense of the word. "Today you can defriend someone. In the past, you were defriended," said Wouter van Wingerden, a linguistic consultant with the Society for the Dutch Language.
The other reference is found in Psalm 88:8, translated in the King James Bible as "Thou hast put away mine acquaintance far from me." The Dutch version quoted in the Woordenboek might be close to 400 years old but it is definitely more concise. It reads 'Mijn vrienden hebt ghy my ont-vrindt,' which translates to "My friends thou hast defriended."
The word fell into disuse after the 17th century, perhaps because the Netherlands had few friends left. By 1672, the young Dutch republic found itself at war with France, England, and the dioceses of Cologne and Munster.
Similarly, unfriend, the New Oxford American Dictionary Word of 2009, is dated by the OED back to 1659. For further thoughts on the revival of unfriend and ontvrienden, see my latest Word Routes column on the Visual Thesaurus, "'Sleeping Beauties' in English and Dutch."