An Etymological Dictionary of the German Language/Annotated/können
können, preterite present, ‘to be able,’ from Middle High German kunnen, Old High German chunnan, preterite present (singular kan, plural kunnum, preterite konsta), properly ‘to be capable intellectually, know, be acquainted with, understand,’ then also ‘to be able, be in a position (to).’ Anglo-Saxon cunnan (singular can), preterite present, ‘to be acquainted with, know, be able,’ English can; Gothic kunnan (singular kann, plural kunnum), preterite present, ‘to be acquainted with, know.’ In the earlier periods the verbal stem können had exclusively an intellectual sense in contrast to that of mögen, vermögen. Besides the stem kann- preserved in the verb kunnan (compare also Gothic kunnan, ‘to recognise,’ Anglo-Saxon cunnian, ‘to explore, attempt,’ see also Kunst, kund, and kennen), there exists in the Old Teutonic languages a verbal stem which may be represented in Gothic as *knê, *knô; Anglo-Saxon cnâwan, ‘to recognise, know,’ English to know; Old High German irchnâan, bichnâan, ‘to recognise’; Old High German úrchnât, feminine, ‘perception’ (Gothic *knêþs, feminine, is wanting); the Old High German nominal verb irchnuodilen, ‘to become perceptible,’ points to a Gothic *knôþla-, ‘knowledge.’ The three Teutonic stems kann, knê, knô occur in the non-Teutonic languages, Greek and Latin gnô in γιγνώσκω (ἔ-γνω-ν), ‘to recognize,’ γνῶσις, ‘knowledge,’ Latin gno-sco, nô-tus, nô-tio; Old Slovenian znają, znati, ‘to recognise’; Old Irish gnáth, ‘acquainted.’ Indian forms a present from a root *jan, the preterite from a root jnâ, jânãmi, jajnáu (compare participle jnâtá), ‘to know’; the Teutonic root kann from gen-n appears in Lithuanian żinaú, ‘to know, recognise, perceive,’ pa-żintis, ‘knowledge,’ Zend â-zaiñti, feminine, ‘information,’ Old Irish ad-géin, perfect, ‘cognovit.’ This wide ramification of the closely allied Aryan root gen, gnô, ‘to recognise, know,’ is generally recognised, but its connection with the root gen, ‘to beget, bring forth,’ and the variants gnâ-, gnô-, discussed under Kind, König, and kennen, is problematical. Both seem to be united in Anglo-Saxon cennan, ‘to bring forth,’ and ‘to generate,’ Greek γνωτός, ‘related by blood,’ and ‘discernible, known.’ The distinction, however, between the physical and intellectual senses of the word must have been made previous to the division of languages, since it exists in all the Aryan groups. Compare kühn.