Neil "Neil" is a reduced form of the surname "McNeil" (from the Gaelic "Mac Néill", "son of "Niall""), or variant form the surname of Neill (from the Irish "Ó Néill" or the Scottish Gaelic "Mac Néill", meaning "descendant of "Niall"" and "son of "Niall"". The name passed from Ireland to Scotland where it had the "Mc/Mac" prefix. Some Scottish McNeill's returned to Ireland in the 14th century and are associated with "MacNeill", "MacGreal", "MacReill", and "Mag Reil" surnames. The Manx version of the name is "Kneal" (1598), "Kneale" (1655), or "Kneel" (1636). It evolved from McNelle (1408) and MacNeyll (1430) becoming
McKinley (surname) nickname given the deposed MacDunleavy dynasty royals while exiled in Tirconnell and elsewhere. Being, also, one of Ireland's ancient hereditary medical families, the MacDunleavy (variant English spelling MacDonlevy) were in Tirconnell accorded the high Gaelic status of "ollahm leighis" or the official physicians to the O'Donnell clan in County Donegal and practiced as physicians while exiled in Argyll, Scotland. The nickname was Mac an Leigh. Per this scenario the Gaelic language patronymic forming prefix "Mac" (meaning "descended of") is joined to the Gaelic language "Léigh" meaning leech, but denoting a physician. Leeching (medical) having been for millennia, in Gaelic Ireland