According to "A Dictionary of First Names," by Hanks and Hodges, "Glbert" is of Germanic origin and was introduced into England by the Normans. It consists of two elements, "gisil" meaning "pledge" + "berht" meaning "bright" or "famous." Thus a "public oath" or "well known vow"
In Gaelic Scottland, the name "Gilbert" was used in an early period to render the name "Gille Brighde", meaning servant of St. Bridget."