тоска́

uncommon #5673C1

nounfeminineinanimateuncountable

1.
melancholy, anguish, depression, grief
На душе тоска́ и пустота́.
There is only melancholy and emptiness in my heart.
Often of a vague, heavy sadness with no clear cause.
2.
longing, yearning
Его му́чила тоска́ по до́му.
He was tormented by homesickness.
With по + dative: тоска по дому 'homesickness'.
3.
boredom, ennui, weariness
От э́тих ле́кций одна́ тоска́.
These lectures are nothing but boredom.
Colloquially тоска! means 'how boring!'

Usage info

тоска́ по ро́дине: homesickness

День, укорачивавшийся с каждой неделей, наводил тоску.
The day, growing shorter with each passing week, was depressing.
Туча, нагоняющая тоску, закрыла всё небо.
A cloud bringing on melancholy covered the entire sky.
Его мучила неизбывная тоска по родине.
He was tormented by an unending longing for his homeland.
Э́то уника́льное сре́дство, сгоняющее стресс и тоску́.
It's a unique device able to make stress and melancholy vanish.
В его глазах читалась неизбывность старой тоски.
The endlessness of his old yearning was visible in his eyes.
Тоска сглодала его за эти годы.
Sorrow gnawed away at him over those years.
Не давай тоске загрызать тебя, отвлекись.
Don’t let sadness eat you up; distract yourself.
Тоска, снедавшая его годами, вдруг отступила.
The longing that had tormented him for years suddenly receded.

This noun exists in singular form only.