Clubhead with a hollowed-out back and thin middle of the face, with the weight distributed around the perimter on the back creating thicker edges and a larger sweetspot. Considered game improvement ir [..]

Irons that have a hollowed out area at the back of the club. This is so that the weight taken out can be redistributed elsewhere. The redistribution of weight then creates a more forgiving club.

The Cavity Back is a special construction of golf clubs. Those are irons, in which the mass is mostly shifted to the edge of the clubhead, and the back of the clubhead has been hollowed out, so that a cavity results. Therefore the Cavity Back received its name. Because of its special design, this type of irons forgives more mis-hits.

the type of club that removes weight from the back of the clubhead producing a cavity. That weight is then moved to the perimeter of the club (see perimeter weighting)

any iron whose design characteristic is such that the weight is distributed primarily around the outer edges of the clubhead in order to maximize forgiveness on off-center hits.

– Cavity back irons have a design feature that redistributes the weight of the club head from the middle to the perimeter of the club-head. The redistributed weight allows for greater forgiveness on m [..]

The design of an iron head in which the weight is distributed around the perimeter of the head. Cavity backs are easily identified as having a recessed area on the back of the head. Cavity back irons [..]

An iron on which the clubhead features a thin face with a hollowed-out area on back, distributing the weight around the perimeter (contrast with "blade" or "muscleback") The weighting of cavity back clubs allows for a much larger sweet spot, which provides help on mis-hits. Cavity back irons are preferred by mid- [..]

The design of an iron head in which the weight is distributed toward the perimeter of the head. Cavity backs are easily identified as having a recessed area on the back of the head.

A newer design of irons where the back of the clubhead is hollowed out.