Someone who believes in or supports solidarity, especially in politics or society.
The word solidarist can make people think of working together, helping each other, and fairness.
Examples:
The solidarist believes in helping others.
She is a solidarist and wants to make things fair for everyone.
The solidarist works to make things better for everyone.
The solidarist wants to help everyone, even the animals!
The solidarist works day and night to help everyone in the town.
The solidarist is always thinking of ways to help others.