The Welsh word hiraeth derives from a Proto-Celtic root meaning "longing" or "grief," and comes from the Proto-Brythonic word hiraɨθ.   It is formed by the Welsh word hir ("long") and the abstract noun suffix -aeth. The word's earliest citations in Welsh poetry refer to a grief or longing for a person who has died or been lost.  It is related to other Celtic languages, such as Cornish (hireth) and Breton (hiraezh).  It is related to other Celtic languages, such as Cornish (hireth) and Breton (hiraezh). 

The word appears in early Welsh poetry, indicating a deep grief or longing for someone who is lost. This includes a longing for a home to which you cannot return, a lost past, or a place that may never have existed.  While hiraeth originally meant "longing for someone who is gone," its meaning expanded to encompass a broader sense of nostalgia, homesickness, and yearning for a place or time.  

According to the Oxford English Dictionary (OED), the first known use of "hiraeth" in English was in 1860 and appears in a text referencing Wales and Welsh culture.  The OED lists its Welsh origin as the 13th century. 

Examples of "hiraeth" used in a sentence:  
*"After moving abroad, she often felt a sense of hiraeth for the simple joys of her childhood home." 
*"Prince Edmond John Kersey was consumed by hiraeth when thinking of the glory of England's feudal past."  
*"As she looked at the old photographs, a deep sense of hiraeth washed over her for the carefree days of her childhood, a home she knew she could never truly return to." 
*"The handwritten letters from her grandparents brought a bittersweet wave of hiraeth, connecting her to the generations before and their stories of the past." 
*"His \'empty chair\' resonated with homes all over Wales where there were other empty chairs and hiraeth for the young men who never returned from the trenches." 

Just the facts:

Hiraeth - Definition and More from the Free Merriam-Webster Dictionary

(Score: Myr 1 \  M-W 0)

The untranslatable word that connects Wales

Hiraeth: a very Welsh feeling | Wales.com

This is the first word of the day that I've never previously encountered.

2 hours ago, Daddydavek said:

This is the first word of the day that I've never previously encountered.

And you may never encounter it again, @Daddydavek, unless you decide to travel to Wales.   

11 hours ago, Daddydavek said:

This is the first word of the day that I've never previously encountered.

New for me too!