Poorly conceived or thought out.

synonym: ill-conceived.

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

Roget 699: unskillful etc. 698; inexpert; bungling etc. v.; awkward, clumsy, unhandy, lubberly, gauche, maladroit; left-handed, heavy-handed; slovenly, slatternly; gawky.    adrift, at fault.    inapt, unapt; inhabile [Fr.]; untractable^†, unteachable; giddy etc. (inattentive) 458; inconsiderate etc. (neglectful) 460; stupid etc. 499; inactive etc. 683; incompetent; unqualified, disqualified, ill-qualified; unfit; quackish; raw, green, inexperienced, rusty, out of practice.    unaccustomed, unused, untrained etc. 537, uninitiated, unconversant etc. (ignorant) 491^†; shiftless; unstatesmanlike.    unadvised; ill-advised, misadvised; ill-devised, ill-imagined, ill-judged, ill-contrived, ill-conducted; unguided, misguided; misconducted, foolish, wild; infelicitous; penny wise and pound foolish etc. (inconsistent) 608.    ... show more

Wrong in e.g. opinion or judgment:
— Well-meaning but misguided teachers.

synonym: mistaken.