Source : Webster's Revised Unabridged Dictionary (1913)

Lengthways \Length"ways`\ (-w[=a]z`), Lengthwise \Length"wise`\
   (-w[imac]z`), adv.
   In the direction of the length; in a longitudinal direction.

Source : WordNet®

lengthwise
     adj : running or extending in the direction of the length of a
           thing; "the lengthwise dimension" [syn: {lengthways}]
           [ant: {crosswise}]
     adv : in the direction of the length; "He cut the paper
           lengthwise" [syn: {lengthways}, {longwise}, {longways},
            {longitudinally}]