Ding an sich
Concise Oxford English Dictionary © 2008 Oxford University Press:
Ding an sich /ˌdɪŋ an ˈzɪx/
▶noun (in Kant's philosophy) a thing as it is in itself, not mediated through perception by the senses or conceptualization, and therefore unknowable.
– origin from Ger.
'Ding an sich' also found in these Oxford entries:

