one

First recorded before 900; Middle English oon, Old English ān; cognate with Dutch een, German ein, Gothic ains, Latin ūnus (Old Latin oinos ); akin to Greek oínē “ace on a die”

One as an indefinite pronoun meaning “any person indefinitely, anyone” is more formal than you, which is also used as an indefinite pronoun with the same sense: One (or you ) should avoid misconceptions. One (or you ) can correct this fault in three ways. When the construction requires that the pronoun be repeated, either one or he or he or she is used; he or he or she is the more common in the United States: Wherever one looks, he (or he or she ) finds evidence of pollution. In speech or informal writing, a form of they sometimes occurs: Can one read this without having their emotions stirred?
In constructions of the type one of those who (or that or which ), the antecedent of who is considered to be the plural noun or pronoun, correctly followed by a plural verb: He is one of those people who work for the government. Yet the feeling that one is the antecedent is so strong that a singular verb is commonly found in all types of writing: one of those people who works for the government. When one is preceded by only in such a construction, the singular verb is always used: the only one of her sons who visits her in the hospital.
The substitution of one for I, a typically British use, is usually regarded as an affectation in the United States. See also he¹, they.

Perhaps <Greek -ōnē feminine patronymic