mare /meə $ mer/ BrE AmE noun [countable]
[ Language: Old English ; Origin: mere ]
1 . a female horse or ↑ donkey ⇨ stallion , filly
2 . mare’s nest
a) a discovery that seems important but is actually of no value
b) a confused situation or a very untidy place
3 . British English spoken informal if someone is having a mare, things are going very badly for them at the moment. It is short for ↑ nightmare :
The Arsenal goalkeeper had a mare in the first half.