AS a purveyor of words I'm always interested to find one with no English translation.
The one I found in Lisbon was saudade.
A local explained it to me as "a longing for someone who has gone away, someone who gives you happiness, and you are yearning for news of them, but knowing that news will probably be bad".
That was as close as he could explain it in English. Better, he said, to hear it in fado music and feel it on the streets of Alfama.
You really can in Lisbon's oldest neighbourhood, occupying the slope between the Sao Jorge Castle and the River Tejo.
There are great views of its clustered red roofs from the Miradouro das Portas do Sol - a viewpoint on the main road that marks its upper border.
But getting lost in the labyrinth of its streets, an anguished widow singing fado on your iPod, is the best way to connect with the place.
Getting lost is the whole idea of Alfama.
The streets were built this way - twisting, turning, disappearing and occasionally revealing a hidden courtyard or secret staircase - in order to prevent easy navigation.
This was the whole of the city during the Moorish Domination of the 8th Century and while their buildings have long since been replaced by traditional Portuguese structures, their infrastructure remains.
The idea was that when foreign raiders arrived to attack the city, they would be bamboozled by geography before weapons were even drawn.
Originating in the early 19th Century, the mournful music of fado is now on the UNESCO Intangible Cultural Heritage List.
It originated in Alfama, which by then had survived the 1755 earthquake and tsunami which devastated the rest of Lisbon and had become populated by the city's poorest residents.
These were the families whose previous generations had sent their young men away on ships to discover the the world.
Saudade was what many of their wives, mothers and daughters were left with.
It's still the poor who live in Alfama and today when you see a little old lady shuffling along its streets - 4ft tall and all clad in black signifying she has loved and lost - you do feel it.
Although it's a place of melancholy, this is my favourite part of Lisbon. It's shaded, safe and peaceful. And the people are lovely.
We bought a few shots of jininha - a sickly cherry liqueur - from a lady selling it from her doorway. While I drank it standing on the street an old fella started talking to me from his first-floor balcony. He was housebound, apparently, but it didn't stop him engaging with everyone who walked by.
Every June Lisbon hosts a sardine festival, with makeshift bars and kitchens popping up on every square foot of unoccupied land in the city. I missed it by a few days last time I was there but next time I visit, I'll be taking part. And I'll be staying in Alfama.