Yep, English just borrowed the Greek word as is, so the true meaning is obscure for most people. German kind of borrowed it too, but Germanified it- Flusspferd- literally "river horse" in German. :)
Isn't it useful when languages do this. Likewise, in Mandarin it is 河馬 (he2ma3, 'river horse').
They will even back-calque names for things with Greek roots that were never Greek words in the first place: e.g. a eurypterid (from Classical Greek εὐρύς, wide + πτερόν, wing) becomes 廣翅鱟 (guang3chi4hou4, 'wide wing horseshoe-crab').
Indeed, I love these kind of comparisons (not because any one language is better or more creative or anything like that but simply because it is so interesting). Another one- unexpectedly from Japanese to Spanish- "origami"= "papiroflexia."