New and unusual or experimental ideas, especially in the arts, or the people introducing them.
"Dostoevsky was known for his profoundly avant-garde approach to writing."
Favoring or introducing experimental or unusual ideas.
"The main critique was how avant-garde his essay was."
Avant-garde originates in late Middle English (denoting the vanguard of an army): from French, literally ‘vanguard’. Current senses date from the early 20th century.