the.com/baby monitor

means A device that transmits sound (and often video) from a baby's room to a receiver elsewhere, so parents can listen or watch without being in the room.

from A straightforward compound of 'baby' and 'monitor,' the latter from Latin 'monere,' meaning 'to warn' or 'to advise.' The technology descends from household intercoms, adapted for nursery use once affordable wireless audio (and later video) transmission became practical for home use in the mid-to-late 20th century. No tangled folklore here — just parents wanting ears in two rooms at once.