longitudinal

lon·gi·tu·di·nal

adj
\ˌlän-jə-ˈt(y)üd-^ən-əl, -nəl, British also ˌläŋ-gə-ˈtyüd-\

Definition of LONGITUDINAL

1

: of, relating to, or occurring in the lengthwise dimension <a longitudinal bone fracture>

2

: extending along or relating to the anteroposterior axis of a body or part <a trypanosome which reproduces by longitudinal fission>

3

: involving the repeated observation or examination of a set of subjects over time with respect to one or more study variables (as general health, the state of a disease, or mortality) <a longitudinal study of heart transplant recipients over a five-year period>

—lon·gi·tu·di·nal·ly \-ē\ adverb