ISOCH'RONAL ISOCH'RONOUS, adjective [Gr. equal, and time.] Uniform in time; of equal time; performed in equal times. An isochronal line, is that in which a heavy body is supposed to descend without acceleration. Isochronal vibrations of a pendulum are such as are performed in the same space of time.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI