'ankylosing' originates from Greek, specifically the root 'ankyl-' from 'ankyloō' or 'ankylos', where 'ankyl-' meant 'crooked; bent; fused'.

'ankylosing' developed via medical Latin and Neo-Latin: Greek 'ankylos' / 'ankyloō' → Late Latin/Medieval Latin 'ankylose' (noun/verb) → English adoption in the sense of 'showing ankylosis' (through formations like 'ankylosing' in modern medical usage).

Initially, the Greek root referred to 'crooked' or 'bent'; over time in medical contexts it came to mean 'stiffened' or 'fused' (as in bone or joint fusion), which is the current usage in 'ankylosing'.