You might have been learning Russian for some time, or maybe you just started. You probably know that each language has a set of words that are depend "impossible to translate" or that have no equivalent in our mother tongues.
Vladimir Nabokov, the famous Russian-American author of ‘Lolita,’ put it best: “No single word in English renders all the shades of ‘toska.’ At its deepest and most painful, it is a sensation of great spiritual anguish, often without any specific cause. At less morbid levels it is a dull ache of the soul, a longing with nothing to long for, a sick pining, a vague restlessness, mental throes, yearning. In particular cases it may be the desire for somebody of something specific, nostalgia, love-sickness. At the lowest level it grades into ennui, boredom.”