'O-ethylate' originates from modern chemical nomenclature in English, combining the prefix 'O-' (denoting an oxygen-bound substituent, ultimately from New Latin 'oxygenium') with 'ethylate', where 'ethyl' comes from French 'éthyle' (coined from ether-related roots) and the verb-forming suffix '-ate' derives from Latin '-atus' via French.

'O-ethylate' developed from the 19th-century formation 'ethylate' (from 'ethyl' + '-ate') used in chemical literature; later the locant/prefix 'O-' was appended in systematic nomenclature to specify substitution at an oxygen atom, yielding the modern form 'O-ethylate'.

Initially the root 'ethylate' referred generally to formation of an ethyl derivative (or the ethylate salt/anion); over time the term came to be used specifically for introduction of an ethyl group at a particular atom (here, oxygen), as in 'O-ethylate'.