Toska - noun /หtล-skษ/ - Russian word roughly translated as sadness, melancholia, lugubriousness. "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.
Vladimir NabokovWhile a few pertinent points have to be marked, the general impression I desire to convey is of a side door crashing open in life's full flight, and a rush of roaring black time drowning with its whipping wind the cry of lone disaster.
Vladimir Nabokov