also: 5 technique · 5i
A number describing where a defensive lineman lines up relative to an offensive lineman. Five means outside shoulder of the tackle.
A defensive line alignment on the outside shoulder of the offensive tackle, in the numbering convention where even numbers are head up on a lineman and odd numbers are on a shoulder, counting outward from the center. It is the same physical space the offense describes with gap letters, which means the two sides of the ball carry two different coordinate systems for one piece of ground.
5 techniquethree technique, four technique, seven technique, nine technique, C gapThe scale is standard enough to rely on, but individual staffs drift: there are documented cases of a school shifting the whole scale a notch so that its five is head up on the tackle rather than outside it. The tight end numbers drift most. Worth confirming what a staff means rather than assuming.