Borg armada
In the Spanish language, armada meant a naval fleet, a term that also applied to space fleets.
In 1588, the Spanish Armada was defeated by England. (ENT: "Future Tense")
In 2155 of an alternate timeline, Soval warned T'Pol that if she stayed with a group of Earth ships on its way to the Ceti Alpha system she'd most likely find a Xindi armada waiting for them. (ENT: "Twilight")
In the alternate reality, Christopher Pike described the United Federation of Planets to James T. Kirk as a peace-keeping and humanitarian armada in 2255. (Star Trek)
Three years later in the same universe, the Starfleet Academy long range sensor lab picked up the destruction of a Klingon armada of forty-seven ships over a Klingon prison planet. (Star Trek)
Admiral Terral described the forces fighting the Federation in the 2250s Federation-Klingon War as the Klingon armada. (DIS: "Si Vis Pacem, Para Bellum")
In the late 23rd century, the Klingon Empire sent an armada to destroy the tribble homeworld. (DS9: "Trials and Tribble-ations")
In early 2367, Admiral J.P. Hanson described the starships assembled at Wolf 359 as an armada. (TNG: "The Best of Both Worlds, Part II")
In 2372, a large number of Trabe vessels approached the USS Voyager and were described by Tuvok as an armada. (VOY: "Alliances")
In 2373, after fifteen Borg cubes passed Voyager, Captain Kathryn Janeway ordered Ensign Harry Kim to maintain a long range sensor lock on that armada. (VOY: "Scorpion")
In 2374, Tuvok again described a large number of approaching ships as an armada, this time a number of small and large Caatati vessels. (VOY: "Day of Honor")
In 2375, Onquanii described the series 5 long-range tactical armor unit as capable of flying through an ion storm or an armada of hostile ships and still find its target. (VOY: "Warhead")
In 2378, The Doctor, disguised as Captain Janeway, apparently agreed to have the Voyager meet with a R'Kaal armada and surrender the ship's warp core to them. Chakotay suggested to fight their way out, but "Janeway" replied while they might make it past this armada they could lose many crewmembers in the process or even the entire ship. (VOY: "Renaissance Man")
In 2381, Beckett Mariner rallied the entire California-class fleet to come to the aid of the USS Cerritos after her crew lured the unhinged Texas-class vessels away from Douglas Station. By the time the armada arrived, the crew of the Cerritos had managed to destroy the USS Dallas and USS Corpus Christi by launching her warp core, but this had left her dead in the water and helpless against the USS Aledo. The Aledo was unable to adapt to the arrival of so many ships and continued to prioritize destroying the Cerritos out of spite, leading to its destruction at the hands of the class it had been intended to supplant. (LD: "The Stars At Night")
In the late 24th century, after the Federation learned that Romulus was about to go supernova, Starfleet planned to use a rescue armada of 10,000 warp-capable ferries to relocate Romulan citizens. However, the armada was wiped out in the Attack on Mars. (PIC: "Remembrance")