longitudinal
UK: ˌlɒŋɡɪˈtjuːdɪnəl | US: ˌlɑːndʒɪˈtuːdɪnəl
adj. relating to length or the lengthwise direction of something
adj. (geography) measured or running parallel to the Earth's longitude lines
adj. (research) involving repeated observations over time
Derived from Latin longitudo (length), combining longus (long) with the suffix -tudo (indicating a state or condition). The modern form longitudinal emerged in Late Latin (longitudinalis), later adopted into Middle English via Old French. The morpheme long preserves its core meaning of "length," while -itudinal transforms the noun into an adjective, often used in scientific and geographic contexts to describe alignment or measurement along a linear axis.
The longitudinal study tracked participants' health over 20 years.
The ship sailed along a longitudinal line toward the equator.
Engineers tested the material's longitudinal strength under tension.
Longitudinal waves vibrate parallel to their direction of travel.
The stripes on the fabric run in a longitudinal pattern.