• (aggression) A verbal or physical act of hostility.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• (aggression) Behavior which may be manifested by destructive and attacking action which is verbal or physical, by covert attitudes of hostility or by obstructionism.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2021
• (aggression) Forceful, goal-directed action that may be verbal or physical: the motor counterpart of the affect of rage, anger or hostility. Seen in neurological deficit, temporal lobe disorder, impulse-control disorders, mania, and schizophrenia.
  Sadock's Comprehensive Glossary of Psychiatry and Psychology
  BJ Sadock Titles Press, 2012
• (aggression) Form of behavior which leads to self-assertion; it may arise from innate drives and/or a response to frustration; may be manifested by destructive and attacking behavior, by covert attitudes of hostility and obstructionism, or by healthy self-expressive drive to mastery.
  CRISP Thesaurus
  National Institutes of Health, 2006
• A behavioral interaction between organisms in which one organism has the intention of inflicting physical damage on another individual.
  Gene Ontology Dictionary
  Gene Ontology Consortium, 2021
• Aggressive behavior can denote verbal aggression, physical aggression against objects, physical aggression against people, and may also include aggression towards oneself.
  Human Phenotype Ontology (HPO)
  The Human Phenotype Ontology Project, 2021
• Most patients with mental disorders are not aggressive. Nonetheless, epidemiological evidence points to an increased risk for violence among individuals with a mental disorder compared with the general population.
  Medscape
  WebMD, 2019
• Aggressive behaviour, animal behaviour that involves actual or potential harm to another animal. Biologists commonly distinguish between two types of aggressive behaviour: predatory or antipredatory aggression, in which animals prey upon or defend themselves from other animals of different species...
  Encyclopedia Britannica
  Encyclopedia Britannica, Inc., 2020