magenta (n.) Look up magenta at Dictionary.com
1860, in honor of the Battle of Magenta in Italy, where the French and Sardinians defeated the Austrians in 1859, which advanced the cause of Italian independence and fired the imagination of European liberals. The brilliant crimson aniline dye was discovered shortly after the battle. The town's name traces back to Roman general and emperor Marcus Aurelius Valerius Maxentius (d.312), who supposedly had a headquarters here.