Definitions of modern:

• noun:   a typeface (based on an 18th century design by Gianbattista Bodoni) distinguished by regular shape and hairline serifs and heavy downstrokes
• noun:   a contemporary person
• adjective:   belonging to the modern era; since the Middle Ages

  Example: "Modern art"

• adjective:   characteristic of present-day art and music and literature and architecture
• adjective:   used of a living language; being the current stage in its development

  Example: "Modern English"

• adjective:   relating to a recently developed fashion or style

  Example: "Their offices are in a modern skyscraper"

• adjective:   ahead of the times