Tim Lomas was at Walt Disney World, but not to have fun. He had come to a conference of the International Positive Psychology Association, and he was thinking about a word he had heard for the first time: sisu.

It had been the subject of a talk by a student in HelsinkiThe capital of Finland, situated on the south coast of the country.. "Sisu", she explained, is Finnish for "mental strength which allows someone to overcome extraordinary challenges". It is an important part of Finnish culture, but is something anyone might possess: "It just so happened that the Finns had noticed it and coined a word for it."

It occurred to Lomas that there must be words in other languages that did not have an equivalent in English. He thought it would be interesting to collect the ones that referred to positive states of mind.

So Lomas, a psychology lecturer at the University of East London, set about creating an online dictionary, the Positive Lexicography Project. He asked for suggestions and collected 216 expressions from 49 languages.

He divided them into three groups: relationships, feelings and character. The first included dadirri - Australian Aboriginal for "a deep, spiritual act of reflective and respectful listening" - and the second Geborgenheit - German for "feeling safe from harm". Character words include ilunga - TshilubaOne of the languages spoken in the Democratic Republic of the Congo. for "being ready to forgive a first time, tolerate a second time but never a third time".

Another word he has found is gigil - TagalogA language spoken in the Philippines. for "the irresistible urge to pinch or squeeze someone because they are loved or cherished".

The dictionary reveals many types of happiness. In Sardinian there is ingiogatzau, meaning "joyful joking". In YorubaA language mainly spoken in southwestern Nigeria and Benin. there is iduni, meaning "intense joy".

CreoleA language made by mixing and simplifying two existing ones. In this case it is a variety spoken in Trinidad and Tobago. has bazodee for "dizzy or dazed happiness". Chinese has kǔ qu gan lai for "happiness or relief after going through trying times".

The BakweriA language spoken in southwestern Cameroon. noun womba means "the smile of a sleeping child".

There is a wide debate about whether our language affects the way we think. An extreme position is that if we do not have a word for a particular emotion, we cannot experience it.

Lomas agrees with the first idea but not the second. He believes that studying the words people use for their emotions can help us understand "their ways of constructing happiness, or the things that they recognise as being important".

Yes: When we have a word for something it plants the idea of it in our brain, so we are more likely to notice and experience it. In these difficult times we need as many forms of happiness as possible.

No: We have plenty of words for happiness already. There is no point in cluttering up the language with weird expressions from other ones. Simplicity is the key to successful communication.    

Or... The best experiences in life are so wonderful that we cannot begin to describe them in any language. We should accept that whatever words we have or find are not going to be adequate for the task.