Of, along, or in reference to the direction of the length; longitudinally.(adverb)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "lengthwise" in a sentence
"He slid the knife in lengthwise beneath the skin and then ran a straight incision down the spine all the way to the tail, four feet distant."
"The baby started frantically shaking his head back and forth – the only part of his body free to move – as the doctor used another clamp to crush the foreskin lengthwise, where he then cut."
"Cut each beet in lengthwise quarters, and each quarter into 3 wedges."