The name Geraldo finds its origins in the Germanic languages, specifically deriving from the Old German words "ger" meaning spear, and "waldan" meaning to rule or govern. It emerged during the medieval period, around the 6th to 8th centuries, as a personal name commonly used among Germanic tribes in central and western Europe.

One of the earliest recorded instances of the name can be found in the Codex Diplomaticus, a collection of historical documents from the region of modern-day Germany and Switzerland, dated to the 9th century. It mentions a nobleman named Geraldus, who was a vassal of the Carolingian Empire.

The name gained wider popularity during the High Middle Ages, particularly in regions influenced by the Normans, who had adopted and spread various Germanic names throughout their territories in France, England, and parts of the Mediterranean.

In religious texts, the name is mentioned in the 12th-century chronicles of the Cistercian Order, referring to a monk named Geraldus who served as an abbot in the monastery of Clairvaux in France.

Throughout history, several notable individuals have borne the name Geraldo, including:

1. Geraldo the Painter (c. 1025-1109), a Romanesque artist and illuminator of manuscripts from the Abbey of Saint-Aubin in Angers, France.

2. Geraldo de Barri (c. 1146-1223), also known as Gerald of Wales, a medieval chronicler and archdeacon of Brecon in Wales, who wrote extensively about the history and topography of the region.

3. Geraldo Sempavor (c. 1190-1268), a Portuguese nobleman and military leader who played a significant role in the conquest of the Algarve region from the Moors.

4. Geraldo Mercator (1512-1594), a renowned Flemish cartographer and geographer, best known for his pioneering work in creating the Mercator projection, which is still widely used in navigation and map-making.

5. Geraldo Gomes da Silva (1593-1663), a Portuguese Jesuit priest and missionary who traveled to Japan and wrote extensively about the culture and traditions of the region during the Edo period.

While the name Geraldo has seen a decline in popularity in recent decades, particularly in English-speaking countries, it remains a common name in various Romance language-speaking regions, especially in Portugal, Spain, and parts of Latin America, where it has maintained a strong cultural and historical significance.