From Shawnalenore, via CSECooney:
Saudade:
"A Portuguese word considered untranslatable. One definition: Yearning so intense for those who are missing, or for vanished times or places, that their absence is the most profound presence in one's life. A state of being, rather than merely a sentiment." - Katherine Vaz
"vague and constant desire for something that does not and probably cannot exist ... a turning towards the past or towards the future". - AF Bell
I know that feeling.
I know it far too well.