'forgetfulness-inducing' originates from Modern English, specifically a compound of the noun 'forgetfulness' and the present-participle suffix of the verb 'induce', where 'forgetfulness' is built from 'forget' + '-ness' meaning 'the state of forgetting' and 'induce' comes from Latin.

'forgetfulness' developed from Old English components related to 'forget' (Old English 'forgietan' meaning 'to fail to remember'), and 'induce' comes from Latin 'inducere' (in- + ducere 'to lead'), later passing into Middle English and Modern English; the compound form is a recent Modern English creation combining these elements.

Initially, elements meant 'to fail to remember' (forget) and 'to lead into' (induce); over time they combined in Modern English into a compound meaning 'causing forgetfulness.'