Bouvier called it:
"A contest, authorized by law, in a court of justice, for the purpose of enforcing a right."
In Re Kent, a 1982 British Columbia Supreme Court decision, cited as 139 DLR 3d 318 (also published at 38 BCLR 216), the Court adopted these words:
"The term litigation encompasses the act of carrying on a legal proceeding. A legal proceeding connotes the resolution by a judicial tribunal of an issue between two parties."
The participants - plaintiff, defendant, applicant, petitioner or respondent - are called litigants for so long as the trial is ongoing.