The latest Daredevil teaser from Netflix compares the Man Without Fear to Captain America. Where Cap came on the Marvel movie scene as the First Avenger, Daredevil will arrive as the First Defender, "The Defenders" being the name of the eventual team-up movie to come from Netflix's four Marvel shows, Daredevil, AKA Jessica Jones, Luke Cage and Iron Fist.
The Defenders is a long-running team in Marvel comics, characterized by being made up of characters who aren't the best team players (the classic line up was Doctor Strange, the Hulk, Namor the Submariner, and the Silver Surfer). For its Netflix series, Marvel is repurposing the name, but definitely not the roster, to describe a team of street-based "everyman" characters. Despite their superpowers, Daredevil, Luke Cage and Iron Fist are all much more focused on fighting mob bosses than alien invasions, and Jessica Jones is best known as a superheroine turned private detective.
Aside from rolling out a hint at the series' attitude towards the existence of The Avengers, this teaser also pokes a bit of fun at the common fan reaction to Matt Murdock donning something other than the classic, red Daredevil costume. The answer to fan questions about when and whether it'll appear: "It's a work in progress."