I know of the whinny, the whicker, and the neigh, but what would you call that deep guttural ... it's not a roar, but that long, drawn out scream that would mean like "Don't mess with me I'll stomp your face into the mud" type of roar.
Also, I'd like your take on the definitions of whinny, neigh, snort etc and any others that I didn't mention-- of what a horse could be saying/feeling.
Also, when horses fight do they usually make a lot of noise? Trying to get an idea from videos on YouTube and there is not much vocal stuff going on, so I'm guessing that's just play/excerise, although I did see some Chincoteague stallions in a tif and they didn't make any noise either. I did run across a few teaser vids from mare/stallion and there is of course a lot of verbal interaction.