'peptide-related' originates from English, specifically the compound of 'peptide' and 'related', where 'peptide' ultimately comes from Greek 'peptein' (via Modern Latin 'peptid-') meaning 'to digest' and 'related' comes from Latin 'relatus' (via Old French) where 're-' meant 'again' and the root (from 'ferre') meant 'to carry/bring'.

'peptide' entered scientific English via Modern Latin/Neo-Latin 'peptid-' from Greek 'peptein'; 'related' developed from Latin 'referre/relatus' through Old French; the compound 'peptide-related' is a modern English formation combining these elements to mean 'connected with peptides'.

Initially, roots of 'peptide' were associated with digestion ('to digest'), but the term evolved into a technical chemical/biological term for short chains of amino acids; 'related' originally implied 'brought back/connected' and has come to mean 'connected with' in modern usage; together the compound now specifically means 'connected with peptides'.