from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Lack of wisdom; imprudence or recklessness.
from the GNU version of the Collaborative International Dictionary of English
- n. Want of wisdom; unwise conduct or action; folly; simplicity; ignorance.
from The Century Dictionary and Cyclopedia
- n. Lack of wisdom; ignorance; foolishness; folly; unwise conduct or speech.
Old English unwīsdōm, corresponding to un- + wisdom. (Wiktionary)