What does anno mean?
'Anno' is a Latin word meaning 'in the year', borrowed into English not as a free-standing term but as a component of time-honoured dating formulas. Its most familiar appearance is in 'anno Domini', the phrase behind the abbreviation AD, which counts years from the traditionally reckoned birth of Christ; it also occurs in 'anno regni', used to date events by the years of a monarch's reign, and in older systems such as 'anno urbis conditae', which counted from Rome's legendary founding. Because it is a fossilised phrase rather than a living word, 'anno' belongs to a formal, scholarly register: you will meet it on inscriptions, coins, title pages, and in historical and legal texts far more often than in conversation. Understanding it unlocks the logic of how Western dates were framed for centuries, making it a small but genuinely useful key to reading historical documents.
nounA Latin term meaning 'in the year', used in English chiefly within fixed historical and legal phrases such as 'anno Domini' (in the year of our Lord) or 'anno regni' (in the year of a reign), rather than as an independent word.
- As part of fixed Latin dating formulas, indicating the year in which something occurred (e.g. anno Domini, anno regni).
"The charter was dated anno Domini 1215, in the seventeenth year of King John's reign."
"The inscription reads 'Anno Domini MDCCXLV', marking the chapel's completion in 1745."
"Historians refer to the decree as issued anno regni tertio, in the third year of the king's reign."
Every date you've ever seen labelled 'AD' is quietly using this one little Latin word — 'anno' literally means 'in the year'.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of anno
'Anno' is the ablative case of the Latin noun 'annus', meaning 'year', so the phrase 'anno Domini' translates literally as 'in the year of (our) Lord'. The formula was popularised by the monk Dionysius Exiguus in the sixth century as part of his Easter tables and spread across Europe through medieval charters and church documents. It shares its root with English words such as 'annual', 'anniversary', and 'perennial', all ultimately descended from the same Indo-European year-word.
How anno is actually used
'Anno' is not used freely in modern English; it survives almost exclusively inside traditional Latin dating constructions found on monuments, title pages, coins, and legal documents. It carries a formal, archaic register and is typically italicised when quoted as Latin.
Easily confused with anno
'Anno' is the Latin ablative form meaning 'in the year' used in fixed dating phrases, while 'annual' is an English adjective describing something that happens once a year.