- a young female horse, specif. one under five years of age
- Informal a vivacious young woman or girl
Origin: Middle English filli ; from Old Norse fylja, feminine of foli, foal
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noun pl. fil·lies
- A young female horse.
- Informal A lively, high-spirited girl or young woman.
Origin: Middle English filli, from Old Norse fylja; see pau-1 in Indo-European roots.