dark ages(n = noun.time) middle ages - the period of history between classical antiquity and the Italian Renaissance;
is a kind of age, historic period
is a part of history

N  ignorance, nescience, tabula rasa, crass ignorance, ignorance crasse, unfamiliarity, unacquaintance, unconsciousness, darkness, blindness, incomprehension, inexperience, simplicity, unknown quantities, x, y, z, sealed book, terra incognita, virgin soil, unexplored ground, dark ages, smattering, sciolism, glimmering, dilettantism, bewilderment, incapacity, pedantry, charlatanry, charlatism, Philister, Philistine, ignorant, nescient, unknowing, unaware, unacquainted, unapprised, unapprized, unwitting, unweeting, unconscious, witless, weetless, a stranger to, unconversant, uninformed, uncultivated, unversed, uninstructed, untaught, uninitiated, untutored, unschooled, misguided, unenlightened, Philistine, behind the age, shallow, superficial, green, rude, empty, half-learned, illiterate, unread, uninformed, uneducated, unlearned, unlettered, unbookish, empty-headed, dizzy, wooly-headed, pedantic, in the dark, benighted, belated, blinded, blindfolded, hoodwinked, misinformed, au bout de son latin, at the end of his tether, at fault, at sea, caught tripping, unknown, unapprehended, unexplained, unascertained, uninvestigated, unexplored, unheard of, not perceived, concealed, novel, ignorantly, unawares, for anything, for aught one knows, not that one knows, Int, God knows, Heaven knows, the Lord knows, who knows, nobody knows, ignorance never settles a question, quantum animis erroris inest!, small Latin and less Greek, that unlettered small-knowing soul, there is no darkness but ignorance.

dark, dark adaptation, dark blue, dark bread, dark chocolate, dark cloud, dark comedy, dark field illumination, dark glasses, dark ground illumination, dark horse, dark lantern, dark matter, dark meat, dark red, grope in the dark, in the dark, middle ages