Scrag n.
1. Something thin, lean, or rough; a bony piece; especially, a bony neckpiece of meat; hence, humorously or in contempt, the neck.
Lady MacScrew, who . . . serves up a scrag of mutton on silver. --Thackeray.
2. A rawboned person. [Low]
3. A ragged, stunted tree or branch.
Scrag whale Zool., a North Atlantic whalebone whale (Agaphelus gibbosus). By some it is considered the young of the right whale.