'rootlessness' is formed in Modern English by combining 'root' + the adjective-forming suffix '-less' + the noun-forming suffix '-ness'.

'root' originates from Old English 'rōt' (meaning 'root' of a plant or figurative origin); the suffix '-less' comes from Old English '-lēas' meaning 'without'; '-ness' comes from Old English '-nes(s)a' used to form abstract nouns. These elements combined in later English to yield 'rootless' and then 'rootlessness'.

Originally referring to the literal absence of plant roots or origin, the compound moved from a literal sense ('without roots') to figurative senses like 'without a home' or 'without grounding' over time.