Adamant means refusing to change your mind or position, no matter what arguments or pressure you face. When someone is adamant about something, they've made a firm decision and they're sticking to it.

When your parents are adamant that you finish your homework before playing video games, no amount of pleading or bargaining will change their minds. When a friend is adamant that she saw a shooting star, she's absolutely certain and won't be convinced otherwise.

Being adamant isn't always stubborn or unreasonable. Sometimes it means having strong principles. A scientist might be adamant that proper safety procedures must be followed in the lab. A coach might be adamant that every player deserves equal practice time.

The word can describe both good and bad situations. Someone might be adamantly opposed to cheating. But someone could also be adamant about something incorrect, refusing to listen to facts or reason. The key is that adamant describes the firmness of the stance, not whether the stance is right or wrong.