from the GNU version of the Collaborative International Dictionary of English
- n. The time between; the time between sunrise and noon; specifically, the third hour of the day, or nine o'clock in the morning, according to ancient reckoning; hence, mealtime, because formerly the principal meal was eaten at that hour; also, later, the afternoon; the time between dinner and supper.
from The Century Dictionary and Cyclopedia
- n. Nine o'clock in the morning; the period from nine o'clock to noon; the canonical hour of terce.
- n. Noon or afternoon; also, a noon meal.
Old English undern. Cognate with dialectal Dutch onder, dialectal German Untern, dialectal Swedish undarn. (Wiktionary)