Patronymic, first attested in English in 1612, has a more complex history.
The form patronym, first attested in English in 1834, was borrowed into English from French patronyme, which had previously borrowed the word directly from Greek. These forms are attested in Hellenistic Greek as πατρώνυμος ( patrōnymos) and πατρωνυμικός ( patrōnymikos). In the form patronymic, this stands with the addition of the suffix -ικός ( -ikos), which was originally used to form adjectives with the sense ‘pertaining to’ (thus 'pertaining to the father's name'). The first part of the word patronym comes from Greek πατήρ patēr 'father' ( GEN πατρός patros whence the combining form πατρο- patro-) the second part comes from Greek ὄνυμα onyma, a variant form of ὄνομα onoma 'name'.
The usual noun and adjective in English is patronymic, but as a noun this exists in free variation alongside patronym.
