Define solidarity . solidarity synonyms, solidarity pronunciation, solidarity translation, English dictionary definition of solidarity . n. Unity of purpose, interest, or sympathy: People gathered to show solidarity with the earthquake victims. American Heritage® Dictionary of the English... support by one person or group of people for another because they share feelings, opinions, aims, etc. Demonstrations were held as a gesture of solidarity with the hunger strikers. Want to learn more? Definition of solidarity noun in Oxford Advanced Learner's Dictionary. Solidarity is the agreement and support between the members of a group, especially a political group. Learn more about the word's meaning , synonyms, collocations, and usage in different contexts from Cambridge Dictionary. Solidarity definition : Unity of purpose, interest, or sympathy.