Noun: ennui (countable and uncountable, plural ennuis)

1. A gripping listlessness or melancholia caused by boredom; depression.
2. ennui m (plural ennuis)
3. (uncountable) Boredom; lassitude.
4. 1832, Honoré de Balzac, La Femme de Trente Ans, Chapter 3,
5. Notre ennui, nos mœurs fades sont le résultat du système politique. — Our boredom, our insipid customs, are the result of the political system.
6. (uncountable...

Verb: ennui (third-person singular simple present ennuis, present participle ennuying, simple past and past participle ennuied or ennuyed)

1. (transitive) To make bored or listless; to weary.

The Course of Theoretical Physics is a ten-volume series of books covering theoretical physics that was initiated by Lev Landau and written in collaboration with his student Evgeny Lifshitz starting in the late 1930s. It is said that Landau composed much of the series in his head while in an NKVD prison in 1938-1939. However, almost all of the actual writing of the early volumes was done by Lifshitz, giving rise to the witticism, "not a word of Landau and not a thought of Lifshitz". The first eight volumes were finished in the 1950s, written in Russian and translated into English in the late 1950s...