'neuron-dense' is a modern compound formed from 'neuron' and 'dense'. 'neuron' originates from Greek, specifically the word 'neûron', where it meant 'sinew, tendon, nerve'. 'dense' originates from Latin, specifically the word 'densus', where it meant 'thick, compact'.

'neuron' entered scientific English via late 19th-century usage from Greek 'neûron' through New Latin and modern anatomical terminology; 'dense' came into English from Latin 'densus' through Old French and Middle English. The compound 'neuron-dense' is a recent English formation used in neuroscience literature.

Initially 'neuron' referred broadly to 'sinew' or 'nerve' in Greek and later came to mean the nerve cell in modern biology; 'dense' originally meant 'thick' or 'compact' in Latin and retained that sense. Combined, 'neuron-dense' now specifically denotes 'containing a large number of neurons in a given area.'