'perihelian' originates from New Latin/Modern English formation built on 'perihelion', ultimately from Greek elements 'peri-' and 'helios', where 'peri-' meant 'around, near' and 'helios' meant 'sun', with the adjectival suffix '-ian' meaning 'relating to'.

'perihelian' was formed in Modern English from the noun 'perihelion' (from New Latin 'perihelion'), which itself derived from Greek 'peri-' + 'helios'. The adjectival form developed by adding the English/Latin suffix '-ian' to denote relation to perihelion.

Initially the root components meant 'around the sun' or 'near the sun'; over time the formation 'perihelian' came to mean specifically 'relating to or occurring at perihelion (the closest orbital point to the Sun)'.