1. Regarding an inclination or a pretence of an inclination to dispute or to disagree, even to engage in law suits: Mrs. Small had a litigious and acrimonious attitude instead of trying to work things out with negotiations.
2. Referring to a person who constantly brings or who prolongs legal actions; particularly when the legal maneuvers are unnecessary or unfounded: Litigious people often enjoy legal battles, the controversy, the courtroom, and the spotlight, so they use the courts to punish enemies, to seek profits, and to pursue minor issues which do not deserve judicial attention.
3. Etymology: from the late 14th century, "fond of disputes", from Latin litigiosus "contentious, quarrelsome"; from litigium, "dispute, strife" which is related to litigare, "to dispute, to quarrel, to strive," from litem, "lawsuit, dispute, quarrel, strife" + root of agere, "to drive, to conduct".

Paranoia in which the patient institutes or threatens to institute legal action because of an imagined persecution.