The action or process of inquiring or searching into matters, esp. for the purpose of finding out the truth or the facts concerning something…

The action of seeking, esp. (now always) for truth, knowledge, or information concerning something; search, research, investigation, examination.

An inquiry or investigation into the nature of or truth about something; (also) the action of conducting such an inquiry. Now usually with into.

Any inquiry or investigation. Also: the object of an inquiry. Obsolete.

Systematic investigation or inquiry aimed at contributing to knowledge of a theory, topic, etc., by… As a mass noun.

The action of carrying out research; an instance of this.

figurative. The action of studying hard. U.S.

The action of finding facts; the work involved in discovering and establishing the facts of a matter.

The rapid or systematic searching of textual material for particular information or features.

Also more fully oppo research: = opposition research n. at opposition, n. compounds 2.