Adverb
In the direction of length.
Source: Webster's dictionaryHe cut the paper lengthwise Source: Internet
longitudinally measured Source: Internet
We studied the development of the children longitudinally Source: Internet
Its structure is different from the other veins in that the smooth muscle in its tunica media (the middle layer of the vessel) is arranged in conspicuous, longitudinally oriented bundles. Source: Internet
It may be longitudinally zoned. Source: Internet
Note each palm leaf section was only several lines, written longitudinally across the leaf, and bound by twine to the other sections. Source: Internet