teach: [OE] To teach someone is etymologically to ‘show’ them something. The word goes back ultimately to the prehistoric Indo-European base *deik- ‘show’, which also produced Greek deiknúnai ‘show’ (source of English paradigm [15]) and Latin dīcere ‘say’ (source of English diction, dictionary, etc). Its Germanic descendant was *taik-, which produced English token and German zeigen ‘show’. From it was derived the verb *taikjan, ancestor of English teach. => diction, dictionary, paradigm, token
