'non-ankylosing' originates from English, combining the negative prefix 'non-' (from Latin 'non' meaning 'not') with 'ankylosing', which ultimately comes from Greek 'ankylōsis', where 'ankyl-' meant 'bent, crooked' and '-osis' indicated a condition.

'ankylosing' developed from medical/Latin usage (Late Latin/Medieval Latin 'ankylosis' from Greek 'ankylōsis'), entering English as 'ankylosis' and later forming the adjective 'ankylosing' (present-participle form); 'non-ankylosing' is formed by prefixing the English negative 'non-' to that adjective.

Originally the Greek root 'ankyl-' referred to 'bent' or 'crooked'; over time 'ankylōsis' came to denote a medical condition of stiffness or fusion (especially of joints). 'Ankylosing' came to mean 'causing or relating to ankylosis', and 'non-ankylosing' accordingly means 'not causing or characterized by ankylosis'.