unity or agreement of feeling or action, especially among individuals with a common interest; mutual support within a group

factory workers voiced solidarity with the striking students

an independent trade union movement in Poland which developed into a mass campaign for political change and inspired popular opposition to Communist regimes across eastern Europe. Formed in 1980 under the leadership of Lech Wałęsa, it was banned in 1981 following the imposition of martial law. Legalized again in 1989, it won a majority in the elections of that year