English has adopted a rich store of words about feeling and suffering from the classical languages. The Greek pathos, for example, has come down to us intact to mean, in English, an evocation of pity or compassion, but that’s just for starters.
Pathology (the word literally means “the study of feeling or suffering”) is the branch of medical science concerned with investigating the nature of disease. It also refers to deviation in not only physical and mental health but also, by extension, environmental and social ills.
A class of terms referring to specific physical and mental ailments uses the root -pathy: They include allopathy, the name for the conventional treatment of disease, often with pharmaceuticals that counter or alleviate symptoms, and its complement homeopathy, which refers to treatment by natural substances.
Words like arthropathy (joint disease) and cardiopathy (heart disease) identify ailments of specific organs or body systems, while noun and adjectival forms of the names of the mental disorders psychopathy and sociopathy (referring to behavior marked by antisocial behavior), have transcended the medical milieu to be used loosely in popular culture.
Phytopathology, or plant pathology, meanwhile, is the study of plant diseases. These ailments, and those affecting animals as well, are generally caused by pathogens (there’s that root word again, followed by another common root, which stems from the Greek term meaning “to be born”).
Forms of other -path terms besides psychopath and sociopath are also used outside of the medical realm: Sympathy, the sensitivity to others’ feelings, and empathy, the action of, or the capacity for, vicarious experience of others’ feelings; sympathetic and empathetic are the adjectival forms. Then there’s apathy, meaning “the lack of feeling,” and antipathy, which means “aversion.” Each has a corollary adjectival form, though antipathetic is less commonly used than apathetic.
Speaking of -pathetic, that’s a word in its own right, with several distinct meanings: It can mean “sad,” “laughable,” “inadequate,” or, less often, “able to arouse compassion or contempt.”
Note, too, related terms derived from -pati, the Latin equivalent of -path: Compatible is essentially a synonym of sympathy. Meanwhile, passion (“suffering”) and both forms of patient — the noun referring to someone under medical care or treatment and the adjective for the quality of forbearance — stem from this root.