'Investigation' definitions:

Definition of 'investigation'

From: WordNet
noun
An inquiry into unfamiliar or questionable activities; "there was a congressional probe into the scandal" [syn: probe, investigation]
noun
The work of inquiring into something thoroughly and systematically [syn: investigation, investigating]

Definition of 'Investigation'

From: GCIDE
  • Investigation \In*ves`ti*ga"tion\, n. [L. investigatio: cf. F. investigation.] The act of investigating; the process of inquiring into or following up; research; study; inquiry, esp. patient or thorough inquiry or examination; as, the investigations of the philosopher and the mathematician; the investigations of the judge, the moralist. [1913 Webster]

Synonyms of 'investigation'

From: Moby Thesaurus