Antoniou is a Greek patronymic surname written Αντωνίου. It is the genitive form of the personal name Antonios (Αντώνιος), so its practical sense is “of Antonios” and, in a family-name context, “son or descendant of Antonios.” The surname describes how a family was identified; it does not supply a separate dictionary meaning for the ancestor's name and does not indicate one common Antoniou lineage.
How Antonios Becomes Antoniou
The crucial change is grammatical. Greek is an inflected language, and a name changes form according to its role in a phrase. Antonios is the nominative form used for the person named Antonios; Antoniou is its genitive, the form used for “of Antonios.” The Dictionary of American Family Names accordingly defines Antoniou as a Greek patronymic “from the genitive case” of Antonios.
This way of expressing a patronymic has deep roots in Greek naming practice. The University of Oxford's Lexicon of Greek Personal Names explains that an ancient patronymic normally put the father's name in the genitive: Alexandros Philippou meant “Alexander, son of Philip.” That ancient example explains the grammar, not the age of the modern surname. It would be unsafe to infer that a present Antoniou family has a documented line back to antiquity.
When a genitive patronymic became a fixed family name, the relationship label survived after it stopped changing with each generation. More than one household could therefore have acquired Antoniou from an ancestor called Antonios. Shared spelling alone cannot establish that two bearers descend from the same man.
The Name Behind the Surname
Antonios is the Greek member of the name family that includes Latin Antonius and English Anthony. The Oxford dictionary traces the surname through Antonios to that Latin personal name. It also notes that the personal name became widespread in Christian societies particularly through devotion to Saint Anthony of Egypt (c. 251–356), with later popularity reinforced by Saint Anthony of Padua (1195–1231). That history helps explain why names from this base could generate unrelated patronymic surnames in different places.
Popular claims that Antoniou literally means “priceless,” “invaluable,” or “flower” are not supported by the checked surname dictionary. It explains Antoniou as the genitive patronymic of Antonios, while its related Anthony entry specifically rejects the supposed derivation from Greek anthos, “flower,” as a historical error that influenced the English spelling with th. Because the entry gives no literal gloss for the older Antonius, that older personal-name meaning is best left unresolved here. The defensible literal explanation of Antoniou itself is “of Antonios.”
Greece, Cyprus, and the Fixing of the Name
Antoniou belongs to the wider Greek naming tradition, but the genitive pattern is especially important in Cyprus. In a study of rural life and naming in Venetian Cyprus, historian Marina Ilias found surnames formed from a person's given name in the genitive. She notes that using a father's first name in this way remained common in Cyprus, particularly in the early twentieth century under British rule, and that many Cypriot family names consequently have the sense “son of X.” This does not date every Antoniou family to that period; it shows a documented setting in which the form could become hereditary.
The surname is not confined to Cyprus: the Oxford dictionary classifies it as Greek and gives Greece as its origin. The Republic of Cyprus open-data portal provides a strong record-level resource for its Cypriot distribution: the nationwide citizen-surname dataset includes surname, year of birth, district, and sex, with coverage stated as 1899–2016. These sources support an association with both Greece and Cyprus, but they do not make the -ou form an exclusively Cypriot surname.
For a separately measurable diaspora example, the U.S. Census Bureau's 2020 surname table recorded 631 people as Antoniou, compared with 572 in its 2010 table. These are counts in U.S. census returns, not estimates of a worldwide family or evidence that the people counted are related.
Greek and Roman-Alphabet Forms
The Greek spelling Αντωνίου is the best anchor for identifying the surname. Antoniou is its standard Roman-alphabet transcription: the Hellenic National Passport and Secure Document Center uses the ELOT 743 system, equivalent to ISO 843, and the Republic of Cyprus's official conversion table renders Greek ω as o and ου as ou. A written accent may appear in linguistic transliteration as Antoníou, but it is normally omitted in English-language records.
Not every similar name is a spelling variant:
- Antonios is the underlying given name, not normally a variant of the surname Antoniou.
- Antoniades/Antoniadis and Antonopoulos are separate Greek patronymic formations from the same personal-name base. A shared base does not make their bearers branches of an Antoniou family.
- Antonio is also a surname and personal name in other language traditions; resemblance is not proof that a record concerns an Antoniou.
- Tony is documented by the Oxford dictionary as an Americanized form of Antoniou in some families. It should be treated as a possible record transition, not an automatic equivalent for every person named Tony.
Where a Latin-alphabet record is ambiguous, compare it with Αντωνίου, along with dates, relatives, and places. That is especially important because a record may contain a given name and a surname from the same name family—for example, Antonios Antoniou—without being a clerical duplication.
What the Surname Can and Cannot Tell You
Antoniou reliably indicates a Greek-language patronymic formation from Antonios. Its strong association with both Greece and Cyprus can help frame research, and the original spelling can help reconcile records written in different alphabets. It cannot, by itself, choose between a Greek and Cypriot family history, identify a village, date when a particular branch adopted a hereditary surname, or demonstrate kinship between bearers.
The distinction matters here because Antoniou is structurally capable of repeated formation. A documented parent-child link, locality, and continuity of records are needed before an etymological relationship can be turned into a genealogical claim.
References
- Patrick Hanks and Simon Lenarčič, with Peter McClure, eds., Dictionary of American Family Names, 2nd ed., Oxford University Press, 2022, entries “Antoniou,” “Anthony,” and “Tony.” Licensed entry text displayed by Geneanet.
- University of Oxford, Lexicon of Greek Personal Names, “Naming Practices”, especially “The patronymic.”
- Marina Ilias, Socioeconomic Aspects of Rural Life in Venetian Cyprus, PhD thesis, University of Cyprus, 2021, pp. 132–133. University repository PDF.
- Hellenic National Passport and Secure Document Center, “Greek Letter Transcription Based on ELOT 743”.
- Republic of Cyprus, Permanent Committee for the Standardization of Geographical Names, *Conversion Table of the Greek Alphabet into Roman Characters Based on ELOT 743*, approved by the United Nations.
- Republic of Cyprus, Ministry of Interior, *List of Surnames of Cypriot Citizens*, National Open Data Portal, released 2017, metadata updated 2024.
- U.S. Census Bureau, *Frequently Occurring First Names and Last Names in the 2020 Census*, released April 14, 2026; and *Frequently Occurring Surnames from the 2010 Census*.