dark ages

Short definition from Wiktionary

Noun

1. 1
   Alternative letter-case form of Dark Ages.
2. 2
   plural of dark age

Proper noun

1. 1
   The period of European history encompassing (roughly) 476–1000 CE.
2. 2
   The Greek Dark Ages (c. 1100–750 BCE).
3. 3
   The dark ages of Cambodia (c. 1450–1863).
4. 4
   The dark ages of Laos (c. 1707–1893).
5. 5
   The Dark Ages, 380 thousand to about 1 billion years after the Big Bang.
6. 6
   Any relatively primitive period of time.
7. 7
   Alternative letter-case form of Dark Ages.