The name Maily has its origins in the Celtic language, tracing back to ancient Britain and Ireland during the 5th century AD. It is derived from the Old Irish word "maille," meaning "gentle" or "humble." The name was initially popular among the Gaelic population before spreading to other regions.

One of the earliest recorded instances of the name Maily is found in the Annals of Ulster, an ancient chronicle of Irish history. The text mentions a notable figure named Maily mac Scandail, a prince of the Dál Riata kingdom in modern-day Scotland, who lived in the late 6th century.

In the 9th century, the name appeared in the Old Welsh language as "Meili," referring to a Welsh saint and hermit who lived in Pembrokeshire. Saint Meili's life and teachings were documented in the medieval hagiographies, contributing to the name's religious significance.

During the Middle Ages, the name Maily gained popularity across Europe, particularly in France and England. One notable bearer was Maily de Rouen, a Norman noblewoman who accompanied William the Conqueror during the Norman Conquest of England in 1066.

In the 12th century, Maily de Gournay, a French theologian and philosopher, gained recognition for her contributions to scholastic thought. She was highly respected for her intellect and participated in theological debates with renowned scholars of her time.

Another prominent figure was Maily de Lusignan, a member of the royal House of Lusignan in the Kingdom of Cyprus during the 13th century. She played a significant role in the political affairs of the region and was known for her diplomatic skills.

In the 16th century, Maily Grevill, an English writer and poet, gained recognition for her literary works. Her poetry was celebrated for its lyrical beauty and delicate exploration of human emotions.

While the name Maily has its roots in ancient Celtic cultures, it has transcended geographical boundaries and historical eras, with notable bearers across various regions and time periods, each contributing to the rich tapestry of history and culture associated with this name.