Foal \Foal\, n. [OE. fole, AS. fola; akin to OHG. folo, G. fohlen, Goth. fula, Icel. foli, Sw Lf?le, Gr. ?, L. pullus a young animal. Cf. {Filly}, {Poultry}, {Pullet}.] (Zo["o].) The young of any animal of the Horse family {(Equid[ae])}; a colt; a filly. {Foal teeth} (Zo["o]l.), the first set of teeth of a horse. {In foal}, {With foal}, being with young; pregnant; -- said of a mare or she ass.