inoculate [LME] Originally to inoculate something was to graft a bud or shoot into a plant of a different type. This corresponds to its Latin source inoculare ‘to graft’, from in- ‘into’ and oculus ‘eye, bud’ (as in binocular [E18th] and ocular [E16th]). The horticultural sense dates from the late Middle Ages. As a medical procedure people could inoculate someone from the early 18th century—its first uses referred to treatment against smallpox. See also vaccine.