1. The act of investigating; examination; research.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• ivestigations,
• investifation,
• investiogation,
• investigtion,
• investigaiton,
• investigatios,
• investgations,
• investitgation,
• investigaton,
• investegations,
• investiogations,
• invesitagation,
• investgigation,
• investegation,
• invegtigations,
• investiagation,
• invistagation,
• investagetion,
• investigartion,
• investaigation

• investigating,
• investment,
• investiture,
• investigatory,
• investors club,
• infestation,
• investigator,
• investigate,
• investigative.

The adverb form of the word "investigation" is "investigatively".

The adjective form of the word "investigation" is "investigative".

The plural of the "investigation" can be the "investigations".

The singular of the "investigation" can be the "investigation".