ignoramus
Concise Oxford English Dictionary © 2008 Oxford University Press:
ignoramus /ˌɪgnəˈreɪməs/
▶noun (pl. ignoramuses) an ignorant or stupid person.
– origin C16 (as the endorsement made by a grand jury on an indictment considered to be backed by insufficient evidence to bring before a petty jury): L., lit. ‘we do not know’ (in legal use ‘we take no notice of it’).
'ignoramus' also found in these Oxford entries:
