in foal
/ɪn fˈəʊl/
/ɪn fˈoʊl/
Etymology
Old EnglishMiddle EnglishEnglish
The phrase 'in foal' dates back to Middle English (1300s). 'Foal' comes from Old English 'fola' (a young horse), which is related to Latin 'pullus' (young animal). The structure 'in + noun' to describe pregnancy mirrors older English patterns also seen in 'in calf' (cows) and 'in lamb' (sheep), where the animal's young gives the phrase its name.