'nonfluid' originates from English, formed by combining the prefix 'non-' (from Latin 'non' meaning 'not') with 'fluid' (from Latin 'fluidus', from 'fluere' meaning 'to flow').

'fluid' comes from Latin 'fluidus' (from 'fluere' 'to flow'), passed into Old French and Middle English as 'fluid'; the privative prefix 'non-' has been used in English since Middle English. The compound 'nonfluid' is a modern English formation by prefixation.

Initially it literally meant 'not flowing' (not in a fluid state); over time it has also been used figuratively to mean 'not flexible' or 'resistant to change'.