'baselessness' originates from English formation combining 'base' + the suffix '-less' + the noun-forming suffix '-ness'; 'base' ultimately comes from Old French 'bas' (from Late Latin 'bassus') meaning 'low', '-less' comes from Old English 'lēas' meaning 'without', and '-ness' comes from Old English '-nes(s)e' used to form abstract nouns.

'base' changed from Old French 'bas' (and from Late Latin 'bassus') into Middle English 'base'; the adjectival suffix '-less' (Old English 'lēas') combined with 'base' to form 'baseless' (adjective), and the noun-forming '-ness' was later added to produce 'baselessness' in modern English.

Initially, 'base' often denoted something low (in status or position); over time, combining it with '-less' and '-ness' produced an abstract noun meaning 'the condition of being without basis,' which now specifically means 'lack of foundation or justification.'