Function: noun
Date: 1640
1 : a time during which a civilization undergoes a decline: as a plural capitalized D&A : the European historical period from about A.D. 476 to about 1000 broadly : MIDDLE AGES b often plural often capitalized D&A : the Greek historical period of three to four centuries from about 1100 B.C.
2 a often plural often capitalized D&A : the primitive period in the development of something <in the dark ages of medicine> b often plural often capitalized D&A : a state of stagnation or decline