'symptomless' originates from the Greek word 'σύμπτωμα' (symptoma), where 'sym-' meant 'together' and 'ptoma' meant 'falling'.

'symptoma' transformed into the Latin word 'symptoma', and eventually became the modern English word 'symptom' with the suffix '-less' added to denote absence.

Initially, it meant 'a falling together of signs', but over time it evolved into its current meaning of 'absence of symptoms'.