'aquopentaamminecobaltic' is a coined chemical adjective formed from several combining elements: 'aquo-' from Latin 'aqua' meaning 'water', 'penta-' from Greek 'pente' meaning 'five', 'ammine' from 'ammonia' (the ligand NH3) as used in coordination chemistry, and 'cobaltic' from 'cobalt' with the adjectival suffix '-ic' indicating the cobalt(III) oxidation state.

Each component traces to older sources: Latin 'aqua' produced scientific combining forms like 'aquo-'; Greek 'pente' gave the prefix 'penta-'; 'ammine' arose in 19th-century coordination chemistry terminology from 'ammonia'; 'cobaltic' derives from the element name 'cobalt' (from German/Dutch 'kobalt') plus the '-ic' adjective-forming suffix, producing terms such as 'cobaltic' to denote Co(III) species.

Individually the roots meant 'water', 'five', 'ammonia', and 'cobalt'; combined in modern inorganic chemistry they form a single technical adjective describing a specific ligand set on a cobalt center (one water + five ammonia ligands on Co in the cobaltic oxidation state).