Flat

Receiver releases on a NEARLY HORIZONTAL path directly to the sideline at 0-2 yds depth — gains very little depth as he travels laterally (the route is FLAT — that's literally the name). Common RB or slot route paired with a curl/corner/sit over the top to high-low the flat defender. The path may arc slightly as the receiver flattens out from the snap angle, but it should NEVER read as a steep climbing diagonal.

Demo rendered on @X (outside WR) at 2yd depth. Only the route runner and the QB are shown so the break stays the focus; the same route family scales to any depth a play calls for, and concepts that use this route may set a different depth.

Concepts that use this route: Curl-Flat, Slant-Flat, Stick, Snag, Flood, Y-Cross