LATIN DICTIONARYLexicon Latīnum
noun · neutersecond declension

harmonium

harmonium n (genitive harmoniī or harmonī)
Classical[harˈmɔ.ni.ũː]Ecclesiastical[arˈmɔː.ni.um]

Meaning

  1. New Latinneuteraccordion (a small, portable, keyed wind instrument)
    Musicus, opus harmoniorum.1860, Neues Lausitzisches Magazin, volume 37 (overall work in German), page 491:

Declension

declension
formsingularplural
nominativeharmoniumharmonia
genitiveharmoniī
harmonī		harmoniōrum
dativeharmoniōharmoniīs
accusativeharmoniumharmonia
ablativeharmoniōharmoniīs
vocativeharmoniumharmonia

Origins

Proto-Indo-European *h₂er-der. Proto-Indo-European *h₂r̥-mo-n Ancient Greek *ἁρμων (*harmōn) Proto-Indo-European *-h₂ Proto-Indo-European *-éh₂ Proto-Indo-European *-i-eh₂ Proto-Hellenic *-íā Ancient Greek -ία (-ía) Ancient Greek ᾰ̔ρμονῐ́ᾱ (hărmonĭ́ā)bor. Latin harmonia Proto-Indo-European *-(i)yós Proto-Italic *-ijos Proto-Italic *-ios Old Latin -ios Latin -iusnom. Latin -ium Latin harmonium From harmonia + -ium.

Quick answers

What does harmonium mean in Latin?
harmonium, a noun, means “accordion (a small, portable, keyed wind instrument)”.
What is the genitive of harmonium?
The genitive singular is harmoniī. harmonium is neuter, second declension.
How do you pronounce harmonium?
In classical Latin, [harˈmɔ.ni.ũː]; in ecclesiastical (church) Latin, [arˈmɔː.ni.um].