'faint-hearted' originates from the adjective 'faint' (Old French 'feint', ultimately from Latin 'fingere') and the Old English noun 'heorte' (heart), where 'feint' (via Latin 'fingere') had senses related to 'feign' or 'pretend/weaken' and 'heorte' meant 'heart'.

'faint' as an element appeared in Middle English (e.g. forms like 'feint') combined with 'heart' to produce compounds such as Middle English 'feint-herted' or similar formations, which eventually became the modern English 'faint-hearted'.

Initially the elements conveyed a sense of being weak or feigned in heart (a lack of strength), and over time the compound's meaning settled on 'lacking courage; timid'.