Razbliuto [ros-blee-oo-toe] (noun), Russian
This melancholic, bittersweet word is used to describe lost love. Specifically, it’s a feeling a person has for someone he or she once loved but no longer feels the same way about. It’s a brilliantly succinct word and captures that feeling of the maddeningly ephemeral nature of love.

This book just came in to one of our little libraries.

In Other Words
A Language Lover’s Guide to the Most Intriguing Words Around the World
Christopher J. Moore
Levenger Press

I PM'd CathCoy with this, but I posted too - for old time's sake...