'myelinate' originates from New Latin 'myelin-' (from 'myelinum') plus the English/Latin-derived suffix '-ate', where 'myelin' ultimately comes from Greek 'myelos' meaning 'marrow'.

'myelos' (Greek) gave rise to New Latin 'myelinum', which entered scientific Latin and modern English as 'myelin'; the verb 'myelinate' was later formed in English by adding the suffix '-ate' to create an action verb meaning 'to apply myelin'.

Initially, the root referred to 'marrow' and to substances resembling marrow; over time the term came to denote the specific fatty substance surrounding nerve fibers, and 'myelinate' came to mean 'to form a myelin sheath'.