The Spanish word 'cara' (meaning 'face') comes from the Latin word 'cara', which meant 'face' or 'countenance'. Going even further back, the Latin word derives from the Ancient Greek 'κάρα' (kára), which meant 'head' or 'face'.

This is a great example of how some words maintain remarkably stable meanings over thousands of years - the word has consistently referred to the face or head across Greek, Latin, and Spanish, with very little semantic shift.

Some common Spanish words and expressions that use 'cara' include 'careta' (mask), 'caradura' (shameless person, literally 'hard face'), and 'cara a cara' (face to face). The word is also used in many Spanish idioms, like 'dar la cara' (to face up to something) and 'tener cara' (to have the nerve to do something).

While English doesn't have many common words directly related to the Greek 'kára', we do see this root in some scientific terms. For example, 'cephalic' (relating to the head) comes from a related Greek word 'kephalē' (head). The word 'character' also has distant connections to this root, as it originally referred to a distinctive mark or face.