Mare is a see also of foal.
Foal is a coordinate term of mare.
As nouns the difference between foal and mare
is that
foal is a young (male or female) horse, especially just after birth or less than a year old while
mare is an adult female horse or
mare can be a type of evil spirit thought to sit on the chest of a sleeping person; also the feeling of suffocation felt during sleep; a nightmare or
mare can be (planetology) a dark, large circular plain; a “sea”.
As a verb foal
is (equestrian) to give birth; to bear offspring.