Armida is an opera by Antonín Dvořák in four acts, set to a libretto by Jaroslav Vrchlický that was originally based on Torquato Tasso's epic La Gerusalemme liberata. Dvořák's opera was first performed at Prague's National Theatre on 25 March 1904; the score was published as opus 115 in 1941.

In terms of genre, Armida represents the culmination of Dvořák's experimentation with a Wagnerian style of opera composition, though much of the music belongs to Dvořák's own genre. Vrchlický's libretto parallels the one that Philippe Quinault wrote for Jean-Baptiste Lully in their opera of the same name.^{[citation needed]}

In the royal gardens of Damascus the call to prayer is heard. Ismen enters with news of the approaching Franks, but tries to dissuade the king from an immediate confrontation. He advises sending the king's daughter Armida, who has rejected Ismen's marriage proposal, to sow dissention in the enemy camp. She at first refuses, but when Ismen uses his magic to show her the enemy camp she recognizes Rinald as the knight she has just dreamed of and agrees to undertake the mission.

Armida arrives in the crusaders' camp and meets Rinald, who brings her into the council where she tells them that an uncle has blinded the king, usurped the throne, and chased her into the desert. Rinald urges the Franks to come to her aid at once and proposes he lead the effort. Bohumir, leader of the Franks, prays for guidance and decides they should support Armida, but he will arrange for lots to be drawn to select the expedition's commander. Rinald, too impatient to wait, leaves the camp with Armida. They are caught leaving the Frankish camp by the hermit Peter, but the lovers are aided in their escape by Ismen, who drives a chariot pulled by dragons.

Rinald and Armida are entertained in her garden by sirens and fairies. Ismen disguised as an old man tries to destroy the palace. When he finds his powers no match for Armida's sorcery, he goes to Rinald's companions and claims to be a convert to their Christian faith. Glad to have his help, they accept from him the Archangel Michael's diamond shield, which they use to bring Rinald out of the palace. Armida gives way to grief and the palace collapses.

Rinald asks forgiveness for abandoning his comrades and his mission. As the crusaders advance on Damascus the battle passes through the camp and Rinald kills Ismen and is then confronted by a knight in black. As they battle one another and Rinald curses Armida's name, the knight drops his sword and is stabbed by Rinald, who only then recognizes his opponent is Armida. He baptises her as she dies in his arms.

The opera premiered at Prague's National Theatre on 25 March 1904. It has been revived there several times, in 1928, 1941, 1946, 1948, and 1987. Other Czech performances include Plzen in 1925 and 1943, Brno in 1935 and 1994, Olomouc in 1936, Ostrava in 1941, 1991 and 2012, and Liberec in 1968. The first production outside of Czechoslovakia or the Czech Republic, in Bremen in 1961, included Montserrat Caballé in the cast.^[1]

In 2022, a production shared with Pilsen was presented at Wexford Festival Opera.^[2]

The opera was revived in May 2023 at the Prague National Theater.^[3]