'macrofaunal' originates from a combination of the Greek prefix 'macro-' (from Greek 'makros', meaning 'large') and the Latin-derived noun 'fauna' (meaning 'animals'), with the adjectival suffix '-al' added to form 'relating to fauna'.

'macrofaunal' developed from the compound 'macro-' + 'fauna' -> 'macrofauna' (coined in ecological/biological contexts in the 19th–20th centuries) and later the adjective-forming derivation produced 'macrofaunal'.

Initially formed to denote 'large animals' in a literal sense, it evolved into the ecological term meaning 'relating to animals of a defined larger size class (macrofauna)' used in studies of communities and sediments.