A bass horn (brass wind instrument) that is the tenor of the tuba family.

Roget 417: musical instruments; band; string-band, brass-band; orchestra; orchestrina^†.    [Stringed instruments], monochord^†, polychord^†; harp, lyre, lute, archlute^†; mandola^†, mandolin, mandoline^†; guitar; zither; cither^†, cithern^†; gittern^†, rebeck^†, bandurria^†, bandura, banjo; bina^†, vina^†; xanorphica^†.    viol, violin, fiddle, kit; viola, viola d'amore [Fr.], viola di gamba [It]; tenor, cremona, violoncello, bass; bass viol, base viol; theorbo^†, double base, contrabasso^†, violone^†, psaltery [Slang]; bow, fiddlestick^†.    piano, pianoforte; harpsichord, clavichord, clarichord^†, manichord^†; clavier, spinet, virginals, dulcimer, hurdy-gurdy, vielle^†, pianino^†, Eolian harp.    [Wind instruments]; organ, harmonium, harmoniphon^†; American organ^†, barrel organ, hand organ; accordion, seraphina^†, concertina; humming top.    flute, fife, piccolo, flageolet; clarinet, claronet^†; basset horn, corno di bassetto [It], oboe, hautboy, cor Anglais [Fr.], corno Inglese^†, bassoon, double bassoon, contrafagotto^†, serpent, bass clarinet; bagpipes, union pipes; musette, ocarina, Pandean pipes; reed instrument; sirene^†, pipe, pitch-pipe; sourdet^†; whistle, catcall; doodlesack^†, harmoniphone^†.    horn, bugle, cornet, cornet-a-pistons, cornopean^†, clarion, trumpet, trombone, ophicleide^†; French horn, saxophone, sax [Slang], buglehorn^†, saxhorn, flugelhorn^†, althorn^†, helicanhorn^†, posthorn^†; sackbut, euphonium, bombardon tuba^†.    [Vibrating surfaces] cymbal, bell, gong; tambour^†, tambourine, tamborine^†; drum, tom-tom; tabor, tabret^†, tabourine^†, taborin^†; side drum, kettle drum; timpani, tympani^†; tymbal^†, timbrel^†, castanet, bones; musical glasses, musical stones; harmonica, sounding-board, rattle; tam-tam, zambomba^†.    [Vibrating bars] reed, tuning fork, triangle, Jew's harp, musical box, harmonicon^†, xylophone.    sordine^†, sordet^†; sourdine^†, sourdet^†; mute.    (iv) PERCEPTION OF SOUND ... show more

Dutch: euphonium
Polish: eufonium