small horse; pony
Refers to a horse of small stature, including ponies. Not necessarily a young horse.
There are several small horses at that farm.
foal; colt; filly
Specifically a young horse, typically under one year old. Colt is male, filly is female.
The foal born in spring is running around energetically.
General word for horse, regardless of age or size.
Loanword for pony, often used for specific breeds or in casual contexts.
Standard kanji spelling for a young horse.
Alternate kanji spelling; 仔 also means young animal.
Alternate kanji spelling; 小 means small.
Compound of 子 (ko, 'child') and 馬 (uma, 'horse'), with rendaku voicing of the second element.