: an ankle-high boot with elastic panels along the sides
The Chelsea boot can trace its lineage back to Victorian England where men and women turned to this elastic-sided boot as a practical alternative to the finicky button-boots that were common at that time. Queen Victoria favored it as a riding boot due to its ease to put on and take off. The Chelsea boot would not see a resurgence of popularity until the 1960s, when it was picked up as a fashion item by young British men who were called "mods." … Today, the Chelsea boot, much like the slimmer cuts favored in the 1960s, [has] made a comeback in both men and women's fashion.—Nick Pavio, The Carroll News: John Carroll University, 24 Nov. 2013
Word History
Etymology
from Chelsea, area of west central London; probably so called because the boots became popular in Britain in the 1960's, when King's Road, Chelsea, was considered a pop culture and fashion center