"Undern" derives from Old English "undern" (originally the third hour after sunrise, approximately 9 AM), though its meaning varied historically and regionally, sometimes meaning noon or mid-morning. Medieval poetry used it when specifying times where liturgical hours and solar time reckoning mattered. The term's flexibility and eventual obsolescence reflected changing timekeeping practices—mechanical clocks replaced solar reckoning, making terms like "undern" unnecessary. Poets depicting medieval life employed such vocabulary for authentic period atmosphere, acknowledging that historical cultures divided and named time differently. The word appears in contexts of daily routine, religious observance, or narrative timing where approximate hour designation served structural purposes. Its archaic quality and semantic uncertainty made it valuable primarily for atmosphere rather than precision—"undern" signaled medieval setting more than exact time. The term exemplifies how temporal vocabulary changes with technology and culture, preserving obsolete timekeeping systems in literary language.

“Undern” referred variously to mid-morning or noon, depending on period and region. It was one of the canonical hours of prayer, linking it to monastic life and religious rhythms. Poets might use it to mark the passage of time or to evoke pastoral tranquillity. Understanding historical time divisions deepens awareness of temporal imagery in medieval texts.