Unheard means not listened to or not given attention when speaking. When someone's voice goes unheard, others ignore or dismiss what they're saying, even if it's important. A student with a good idea might feel unheard if classmates talk over them during group work. A younger sibling might complain their concerns go unheard when older family members make all the decisions.

The word also means something never encountered or experienced before. An unheard-of discovery is so unusual or unprecedented that no one has seen anything like it. If your friend claims to have found an unheard-of species of butterfly in the backyard, they're saying it's completely new to science. When someone achieves an unheard-of victory, like winning a championship on their first try, it means the accomplishment is extraordinarily rare.

These meanings connect: both involve something not receiving recognition or acknowledgment. Whether it's a person's words being ignored or an achievement so rare it's never happened before, unheard describes an absence of attention or precedent.