Latin, literally "I do not wish to contend." Latin nolo is first person singular present indicative of nolle "be unwilling." In criminal law, a plea by the defendant that admits no guilt but subjects the defendant to judgment. In effect, a guilty plea, but it allows the pleader to deny the truth of the charges in a collateral proceeding.
1726, in on the qui vive "on the alert," from French être sur le qui vive "be on the alert," from the phrase qui voulez-vous qui vive? sentinel's challenge, "whom do you wish to live?" In other words "(long) live who?" meaning "whose side are you on?" (The answer might be Vive la France, Vive le roi, etc.). From qui (from Latin qui "who") + vive, third person singular present subjunctive of vivre, from Latin vivere "to live" (see viva).