Let’s start with the definition. Hiraeth is an untranslatable Welsh word that describes a longing for a home, a place, or a feeling that no longer exists or never existed.

It’s a homesickness for the places from your past you can’t return to or even those you’ve never been to. Hiraeth can also mean nostalgia for your past self, the people who are long gone, or the emotions you used to feel.

But it can also describe a sense of yearning for imaginary places, feelings, and people – for example, the ones you read about. Sometimes, it feels as if you suddenly take a glance into your previous life and connect with the people and things that existed long ago – or, at least, could have existed.

Hiraeth is a perfect example of a comprehensive term that is impossible to explain with just one or two words. And everyone who is familiar with this rare word puts their own meaning into it.

The Hiraeth of Old Souls and Deep Thinkers
Hiraeth: an Emotional State That Affects Old Souls and Deep Thinkers — by Anna LeMind

https://www.learning-mind.com/hiraeth-deep-thinkers/