'Conscious' once meant 'sharing guilty knowledge' — it shifted to 'aware of one's own mind.'
Aware of and responding to one's surroundings; having knowledge of something; deliberate and intentional; painfully aware of or sensitive to something.
From Latin 'cōnscius,' meaning 'knowing with, privy to, aware,' composed of 'con-' (together, with) and 'scīre' (to know), from the PIE root *skei- (to cut, to split, hence to distinguish, to know by distinguishing). The Latin word originally meant 'knowing something together with another person' — sharing guilty knowledge, being an accomplice. The introspective sense of 'aware of one's own thoughts' developed later, through the philosophical tradition. The word 'science' is a sibling
The Latin root 'scīre' (to know) descends from PIE *skei- meaning 'to cut' — the ancient Indo-Europeans conceptualized knowledge as cutting or splitting, because to know something is to distinguish it from everything else, to carve the world into categories.