Lewis Short
investīgātĭo (noun F) : investigo
* A searching or inquiring into, investigation (class.): rerum occultissimarum,Cic. Fin. 5, 4, 10: veri (with inquisitio),id. Off. 1, 4, 13: sapientiae ejus,Vulg. Isa. 40, 28.
Charlton T. Lewis, Charles Short, A Latin Dictionary