Meaning of "harmonium" in the English dictionary

The pump organ or harmonium is a type of reed organ that generates sound with foot-pumped bellows. More portable than pipe organs, reed organs were widely used in smaller churches and in private homes in the 19th century, but their volume and tonal range are limited, and they generally had one or sometimes two manuals, with pedal-boards being rare. The finer instruments have a unique tone, and the cabinets of those intended for churches and affluent homes were often excellent pieces of furniture. Several million reed organs and melodeons were made in the U.S. between the 1850s and the 1920s. During this time Estey Organ and Mason & Hamlin were popular manufacturers. The melodeon is another reed keyboard instrument, usually housed in a table-like casing, that predates the pump organ. In reference to the music of India, melodeon usually refers to a concertina accordion, while harmonium means the smaller hand-pumped variety.