'non-tendinous' originates from the Latin prefix 'non-' meaning 'not' and from 'tendinous,' which is built on 'tendon' (from Latin 'tendō'/'tendere' meaning 'to stretch').

'tendon' changed from Latin verb 'tendō'/'tendere' ('to stretch') into a noun in Medieval/Old French as 'tendon' (a sinew), entered Middle English as 'tendon,' later forming the adjective 'tendinous' by addition of the suffix '-ous'; the negative prefix 'non-' was then attached to form 'non-tendinous.'

Initially related to the idea 'to stretch' (Latin 'tendere'), it came to mean the anatomical 'sinew' or connective tissue ('tendon'), later producing the adjective 'tendinous' ('relating to or resembling a tendon'); 'non-tendinous' specifically denotes absence of tendon tissue.