The story
From the claim that the rust on an iron bit makes it taste sweet to the horse.
Etymology from Wiktionary, CC BY-SA 4.0.
sweet iron
Today it means: Cold-rolled steel as a material used for a horse's bit. Full definition →
Today it means: Cold-rolled steel as a material used for a horse's bit. Full definition →
From the claim that the rust on an iron bit makes it taste sweet to the horse.
Etymology from Wiktionary, CC BY-SA 4.0.