cogitate
Concise Oxford English Dictionary © 2008 Oxford University Press:
cogitate /ˈkɒdʒɪteɪt/
▶verb formal meditate or reflect.
– derivatives
cogitation noun,
cogitative adjective,
cogitator noun.
cogitation noun,
cogitative adjective,
cogitator noun.
– origin C16 (earlier (ME) as cogitation): from L. cogitat-, cogitare ‘to consider’.
'cogitate' also found in these Oxford entries:

