Examples from the Web for lengthwise
Pull the peppers apart, lengthwise, into halves or large sections, collecting the juices in the platter.
The bundle may be strengthened by putting a good stout cord around it lengthwise and crosswise twice.Fur Farming For Profit|Hermon Basil Laymon
Bake, and cut off a lengthwise slice from each; scoop out potato with a spoon using care that the shells are not broken.Fifty-Two Sunday Dinners|Elizabeth O. Hiller
Cut slit through the wound, lengthwise of limb, two inches long and half an inch deep.