Being a non-participant means not taking part in an activity or event. It could be intentional or unintentional, such as opting out of a group discussion or not being chosen for a team. Being a spectator is another antonym for being a participant, as it involves watching from the sidelines but not actively engaging in the activity. Similarly, being an observer refers to someone who is present but not participating or influencing the proceedings. Refusing to participate, abstaining, or withdrawing are also antonyms for being a participant, suggesting a deliberate choice to not be involved.