— perihelial, perihelian , adj.
/per'euh hee"lee euhn, -heel"yeuhn/ , n. , pl. perihelia /-hee"lee euh, -heel"yeuh/ . Astron.
the point in the orbit of a planet or comet at which it is nearest to the sun. Cf. aphelion . See diag. under aphelion .
[ 1660-70; peri- PERI- + héli ( os ) sun + -on neut. n. suffix, on the model of PERIGEE; earlier in the NL form perihelium ]