Mickey

The proper noun is derived from Mick (“diminutive of the male given name Michael”) +‎ -ey (a variant of -y (diminutive suffix)).

The common noun is derived from the proper noun. Noun senses 1 (“Mickey Mouse cartoon”) and 3.2 (“type of bombsight assisted by radar”) are short forms of Mickey Mouse. Noun sense 2 (“synonym of Mick”) refers to the fact that since the 17th century Michael and its diminutives Mick, Mickey, and Mike have been one of the most common names in Ireland, and that many Irish people are Roman Catholic. Noun sense 3.1 is a short form of Mickey Finn.