暗

to lose hope

attempted assassination

autosuggestion; self-suggestion

Dark Ages

dark age

Proverb

it is darkest under the lamp post; it's hard to see what is under your nose; go abroad to hear of home; you must go into the country to hear what news at London

assassination

to run aground; to strike a rock; to be stranded on a reef

Idiomatic expression

to reach a deadlock; to come to a standstill; to run into difficulties; to hit a snag

to feel gloomy; to feel blue; to feel melancholy

(looking) very bleak; having dim prospects

cryptanalysis

dark clouds gather

threatening signs emerge; trouble is afoot

Dark Continent (i.e. Africa)

to decide the outcome (e.g. game)

to be very different; to be sharply contrasted

shadowy past; murky past

semi-darkness; dim light; poor light; dusk; twilight

dark matter

groping in the dark; exploring new avenues without having any clues

night-vision device

night-vision scope; night scope

dark even in the daytime

dark space

Astronomy

dark nebula

Work of art, literature, music, etc. name

A Dark Night's Passing (novel by Shiga Naoya)

to plot an assassination