Dai
A Welsh nickname surname from a familiar short form of David.
The #7,091 most common surname in the United States (2010 Census) — about 1 in every 65,371 Americans shares it.
Etymology
In Welsh, Dai is a familiar pet form of David, and the surname likely began as a nickname or identifying byname for someone known by that short form. The older Welsh name David comes from Hebrew *Dawid*, meaning “beloved,” though the surname itself is not a direct hereditary form of that root. In some cases, similar-looking surnames may also have been influenced by local or family usage, so not every bearer will share the same origin.
History
The historical excerpts point especially to Wales and Welsh-border usage, where Dai was a common familiar form of David. In English records, surnames could crystallize from nicknames, and a byname like “Dai” could become hereditary over time. Modern bearers may also include people with unrelated surnames from other language traditions, especially outside the British Isles.
Origin
Regions
Variant spellings
Fun fact
In Welsh speech, Dai has long been one of the standard everyday short forms of David, much like Dick for Richard or Bob for Robert in English.
From the historical record
“.69. Rabertu Dai Til. - ■ ; P. T. Yorki”
— A Dictionary of English and Welsh Surnames, with special American instances