'self-knowing' is a compound of 'self' and the present participle 'knowing' in Modern English; 'self' denotes the person and 'knowing' comes from 'know' meaning 'to have knowledge'.

'self' originates from Old English 'self' (from Proto-Germanic *selbaz) meaning 'the same' or 'one's own'; 'know' comes from Old English 'cnāwan' (from Proto-Germanic *knew-), and the present participle form developed through Middle English to form compounds like 'self-knowing'.

Originally the components meant 'one's own' + 'having knowledge'; over time the compound has come to denote the specific idea of being aware of one's inner self and motivations.