'introspectionist' originates from English, specifically formed from the noun 'introspection' plus the agentive suffix '-ist'. The noun 'introspection' ultimately comes via Latin elements: 'intro-' meaning 'inward' and Latin 'specere'/'spectare' meaning 'to look'.

'introspectionist' was formed in modern English by combining 'introspection' (a word established in English from the 17th–18th century via Latin/French influence) with the suffix '-ist' (used to denote a practitioner or adherent), yielding the coined noun 'introspectionist' in later English usage (notably from the 19th–20th century onward in specialized or descriptive contexts).

Initially the components meant 'looking inward' (from 'introspection') and 'one who practices or is concerned with' (from '-ist'); together they have retained the combined modern meaning 'a person who engages in introspection'.