In English, “four-letter word” is a euphemism for “swear word.”
Long ago, someone clever noticed that many offensive words in the English language have four letters. There’s the F-word, of course. And the scatalogical S-word, C-word and P-word. And at least two D-words, and another C-word that is extremely impolite indeed.
Naturally, many other words have four letters. Bob Dylan wrote, and Joan Baez famously sang, a song called “Love Is Just a Four-Letter Word.”
Finnish has a few four-letter words of its own. They have much more in common with “love” than they do with the English F-word. One of them is sisu, that special Finnish combination of courage and perseverance. (As fans of Finland have hardly failed to notice, Sisu is also the title of a very successful – and, yes, quite violent – action movie and its sequel.)
Another Finnish four-letter word, the one we’re here to talk about today, is onni, which refers to happiness, good luck or fortune.
The korvapuusti (11 letters, by the way), the quintessential Finnish cinnamon bun, is sure to contribute to your happiness.Photo: Sabrina Bqain/Finland Image Bank
The International Day of Happiness takes place each year on March 20. To coincide with it, the UN Sustainable Development Solutions Network publishes the World Happiness Report. Since 2018, Finland has occupied the top spot on the report’s list of the happiest countries in the world.
A versatile happiness concept
Finland has fostered an “infrastructure of happiness,” constructing and maintaining the culture and the social institutions that form the basis and framework for individuals and communities to build their happiness. That includes trust, good governance, education, connection with nature, work-life balance, equality and a number of other elements.
Could the word onni itself have anything to do with it? Could it be the new “it” word? The new sisu? A snappy term destined to be on everybody’s lips, at the tip of everyone’s tongue?
Well, umm, hey, sure, why not? If we do say so ourselves.
At the very least, onni serves to show the Finnish language’s versatility. If you’ve got onni, you’re also lucky enough to have a whole family of other words derived from it (see table below), thanks to the handy Finnish grammar system that many of us know and love (to use a couple of English four-letter words).
Embark with us on a voyage into understanding the Finnish language and Finnish happiness. Onnea matkaan! (Good fortune on the trip!)
Going sledding on a wintery hill in Finland brings a happy rush of adrenaline.Photo: Jussi Hellsten/City of Helsinki
Charting Finnish happiness
| Finnish word | Part of speech | English translation |
| onni | noun | happiness, good luck, good fortune, joy |
| Onni | (male name) | (same as above) |
| onnellinen | adjective | happy |
| onnellisuus | noun | happiness |
| onnistua | verb | to succeed |
| Onneksi olkoon! | (salutation, many different occasions) | Congratulations! |
| onnitella | verb | to congratulate |
| onnittelut | noun | congratulations |
| onneksi | noun/adverb | luckily, fortunately |
| onnekas | adjective | lucky, fortunate |
| Paljon onnea vaan | (birthday wishes) | much happiness (sung at birthday parties, to the same tune as the English “Happy Birthday to You”) |
| onnenpotku | noun | stroke of luck (literally: a kick of luck) |
| oman onnen seppä | (saying) | the maker (literally: the smith) of their own fortune |
| Kell’ onni on, se onnen kätkeköön, / kell’ aarre on, se aarteen peittäköön, / ja olkoon onnellinen onnestaan… | (excerpt from “Laulu onnesta” (Song of Happiness), a poem by Eino Leino, published in 1900) | They who have happiness, let them hide it, / they who have treasure, let them cover it up, / and let them be happy about their good fortune… |
By Peter Marten, March 2026
