'encouragingness' originates from French and Old English elements via modern English: the verb 'encourage' comes from Old French 'encoragier' (modern French 'encourager'), where the prefix 'en-' worked as an intensifier or causative and 'corage' (from Latin 'cor' meaning 'heart') meant 'heart' or 'courage'. The abstract noun suffix '-ness' is from Old English '-ness' used to form nouns denoting a state or quality.

'encouragingness' developed from Middle English forms of 'encourage' (borrowed from Old French 'encoragier'), then into the present verb 'encourage', with the adjective 'encouraging' and later the noun-forming suffix '-ness' producing 'encouragingness'.

Initially the root idea focused on 'putting heart into' or 'giving courage'; over time the verb came to mean 'to give support or confidence', and the derived noun 'encouragingness' denotes the abstract quality of being encouraging.