Not knowledgeable about something specified:
— A person unacquainted with our customs.

synonym: innocent.

Roget 491: 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 etc. (uncertain) 475; caught tripping.    unknown, unapprehended, unexplained, unascertained, uninvestigated^†, unexplored, unheard of, not perceived; concealed etc. 528; novel.    ... show more

Having little or no knowledge of:
— Unacquainted with city ways.

synonyms: unacquainted with, unfamiliar with.