'peptide-less' originates from Modern English, a compound of 'peptide' + the suffix '-less'. 'Peptide' ultimately comes from Greek elements related to digestion (see below), and '-less' is from Old English 'lēas' meaning 'free from'.

'Peptide' was coined in scientific usage in the 20th century from Greek roots (see 'peptid-'), referring to short chains of amino acids; the suffix '-less' comes from Old English 'lēas' and developed into Modern English '-less'. The compound 'peptide-less' is a recent, transparent formation used in technical contexts to mean 'without peptides'.

Initially, the Greek root related to 'digested' substances; in modern scientific usage 'peptide' means 'short chain(s) of amino acids'. The suffix '-less' has long meant 'without', and together the compound came to mean 'without peptides'.