horse

1 horse /ˈhoɚs/ noun
plural horses
1 horse
/ˈhoɚs/
noun
plural horses
Britannica Dictionary definition of HORSE
1 
[count] : a large animal that is used for riding and for carrying and pulling things — often used before another noun
— compare colt, filly, foal, gelding, mare, pony, stallion; see also quarter horse, racehorse, workhorse
2 
[count]
a  : a frame used to support a piece of wood while it is being cut with a saw : sawhorse
b  : a large piece of equipment used in gymnastics : pommel horse
3 
horses [plural] informal
b  the horses : horse races
4 
[count] US, informal : an athlete who is strong and who helps a team to win — usually plural

a horse of a different color

chiefly US, informal
: a very different thing or issue

beat a dead horse

(chiefly US) informal or flog a dead horse
1 
: to keep talking about a subject that has already been discussed or decided
2 
: to waste time and effort trying to do something that is impossible

change horses in midstream

: to choose a different leader or policy during a time when serious problems are being dealt with

eat a horse

informal
◊ Someone who is very hungry can be described as being hungry enough to eat a horse.

from the horse's mouth

informal, of information
: from the original source or person and therefore thought to be true

hold your horses

informal
— used to tell someone to slow down, stop, or wait for a short time

look a gift horse in the mouth

: to look in a critical way at something that has been given to you

put the cart before the horse

— see 1cart

the wrong horse

◊ If you choose/pick/back (etc.) the wrong horse, you choose or support someone or something that is not successful.
2 horse /ˈhoɚs/ verb
horses; horsed; horsing
2 horse
/ˈhoɚs/
verb
horses; horsed; horsing
Britannica Dictionary definition of HORSE

horse around

[phrasal verb] informal or British horse about
: to play in a rough or loud way : to engage in horseplay