'weightless' originates from English, specifically formed from the noun 'weight' plus the suffix '-less', where 'weight' meant 'heaviness' and '-less' meant 'without'.

'weightless' was formed in Modern English by combining 'weight' and the suffix '-less' to create the adjective meaning 'without weight'; the adverb 'weightlessly' is derived from that adjective by adding the adverbial suffix '-ly'.

Initially it meant 'without weight', and over time it has retained that core sense, used both literally (no measurable weight) and figuratively (appearing light or buoyant).