More about armamentarium
English armamentarium is taken straight from the Latin noun armāmentārium “armory, arsenal, storehouse for military equipment.” The base of the Latin compound noun is the neuter plural noun arma “arms, weapons,” from which the verb armāre “to fit or equip with weapons” derives. From the verb armāre and the suffix -mentum, used to form concrete objects, the noun armāmentum is formed. The resulting armāmentum is completed by the very common adjective and noun suffix -ārium (from -arius), showing location. Armamentarium entered English in the 17th century in the sense “arsenal.” The broader sense of armamentarium dates from the 19th century.