lon‧gi‧tu‧di‧nal /ˌlɒndʒəˈtjuːdənəl◂, ˌlɒndʒɪˈtjuːdənəl◂ $ ˌlɑːndʒəˈtuː-/ adjective technical

1. relating to the development of something over a period of time
longitudinal study/survey/research etc
a longitudinal study of unemployed workers

2. going from top to bottom, not across:
longitudinal stripes

3. measured according to longitude
—longitudinally adverb

[TahlilGaran] Dictionary of Contemporary English ▲