'azotometer' is formed from 'azote' + the combining form of '-meter'. 'Azote' comes into scientific usage via French 'azote', ultimately from Greek 'azōtos' where 'a-' meant 'not' and 'zōē' meant 'life' (referring to nitrogen's inability to support respiration). The suffix '-meter' comes from Greek 'metron' meaning 'measure'.

'azotometer' was coined in scientific contexts in the 19th century by combining the term 'azote' (used in French and other scientific languages for nitrogen) with the measuring-suffix '-meter', producing English 'azotometer' as a name for instruments that measure nitrogen.

Initially it referred specifically to devices intended to detect or quantify 'azote' (nitrogen); over time the term has continued to denote instruments for measuring nitrogen content, so the core meaning has remained consistent.