'consubstantial' originates from Late Latin, specifically the word 'consubstantialis', where 'con-' meant 'together/with' and 'substantia' meant 'substance' (with the adjectival suffix '-alis').

'consubstantial' changed from the Late Latin word 'consubstantialis' used in theological Latin and was adopted into English (via ecclesiastical/theological usage) as 'consubstantial' in early modern English.

Initially, it meant 'of the same substance' primarily in theological contexts; over time it has also been used more generally to mean 'of the same nature or essence'.