(male) Probably the most successful of all the Old French names of Germanic origin that were introduced to England by the Normans. It is derived from Germanic wil ‘will, desire’ + helm ‘helmet, protection’. The fact that it was borne by the Conqueror himself does not seem to have inhibited its favour with the ‘conquered’ population: in the first century after the Conquest it was the commonest male name of all, and not only among the Normans. In the later Middle Ages it was overtaken by John, but continued to run second to that name until the 20th century, when the picture became more fragmented.
Short forms: Will, Bill.
Pet forms: Willy, Willie, Billy.
Cognates: Irish: Uilliam. Scottish Gaelic: Uilleam. Welsh: Gwilym. German: Wilhelm. Dutch: Willem. Scandinavian: Vilhelm. French: Guillaume. Spanish: Guilermo. Catalan: Guillem. Portuguese: Guilherme. Italian: Guglielmo. Czech: Vilém. Slovenian: Viljem. Hungarian: Vilmos. Lithuanian: Vilhelmas. Latvian: Vilhelms.
English: from Middle English biscop, Old English bisc(e)op ‘bishop’, which comes via Latin from Greek episkopos ‘overseer’. The Greek word was adopted early in the Christian era as a title for an overseer of a local community of Christians, and has yielded cognates in every European language: French évêque, Italian vescovo, Spanish obispo, Russian yepiskop, German Bischof, etc. The English surname has probably absorbed at least some of these continental European cognates. The word came to be applied as a surname for a variety of reasons, among them service in the household of a bishop, supposed resemblance in bearing or appearance to a bishop, and selection as the ‘boy bishop’ on St. Nicholas's Day.