αντάλλαγμα

Etymology: From Ancient Greek ἀντάλλαγμα (antállagma), derived from the verb ἀνταλλάσσω (antallássō) meaning 'to exchange one thing for another'. The word is composed of the prefix ἀντί (antí) meaning 'against, in place of' and ἀλλάσσω (allássō) meaning 'to change, alter'. The concept reflects the fundamental economic principle of giving something to receive something of equivalent value in return.