'anionic' originates from English formation using the noun 'anion' plus the adjectival suffix '-ic'; 'anion' itself comes from New Latin/Modern Latin 'anion', ultimately from Greek 'aniōn' (ἄνιων).

'anionic' was formed in English by adding the suffix '-ic' to 'anion' (a modern chemical term coined in the 19th century from Greek 'aniōn' meaning 'going up'); the modern adjective developed to describe properties of anions in chemistry and materials science.

Initially the root term referred specifically to the ion that moved toward the anode in electrolysis ('the thing going up'), but over time 'anionic' came to mean more generally 'relating to or bearing a negative charge (anions)'.