Pillai or Pillay, (IPA: [piɭːai̯]) meaning "Child of King" (Prince) or "Child",[1] is a surname found among the Malayalam and Tamil-speaking people of India and Sri Lanka.
In Kerala, Pillai is the most common title among upper-caste Nairs,[2][3] often bestowed by the ruling royal families of Kerala[3] and less commonly found among some Brahmins,[4] Nazrani Mappila and Marars of travancore.[3][5]
In Tamil Nadu, it is a common surname among various Vellalar subcastes.[6] It is also used by many Tamil-speaking castes, including Chetti, Rowther, Isai Vellalar, Agamudayar, etc.[7] A minority population of Tamil Pillais, including Vellala, Chetti and Rowther, have migrated and can be found in some parts of Kerala and Karnataka.
In general, the concept of "the Pillai title of Kerala" and "the Pillai surname of Tamilnadu" have two different meanings and no direct relation with each other.
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