Etymology
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ap- (2)

patronymic element in Welsh pedigrees and names, earlier map "son," cognate with Gaelic mac. Since 17c. merged into surnames and reduced to P- or B- (Ap Rhys = Price, Ap Evan = Bevan, Bowen = Ap Owen, etc.).

It is said that a Welshman who evidently was not willing to be surpassed in length of pedigree, when making out his genealogical tree, wrote near the middle of his long array of 'aps' — "about this time Adam was born." ["Origin and Significance of our Names," The Chautauquan, Oct. 1887-July 1888]
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