on the spot (adjective) defenseless: powerless, vulnerable
Sinonime: benighted, catachrestic,
ignorant, inerudite, solecistic, uneducated, unenlightened, ungrammatical, uninstructed, unlearned, unlettered, unread, unschooled, untaught, untutored
Antonime: able,
educated,
learned,
literate,
taught