Press and all the words containing it as a root, as well as a few disguised words from the same source word, pertain in some sense to applying force. This post lists many of the words stemming from the Latin verb premere, meaning “cover” or “hold fast,” and its descendant pressare.
Press itself means “cluster,” “exert force,” “push forward,” and “squeeze out.” As a noun, it refers to a device for applying force, including a printing press, from which influence the word came to describe the collective entity of print media (and later all journalistic media). In that sense, in such phrases as “press conference,” it also acquired adjectival form. It also applies to an approach to applying force, as in a defensive strategy in basketball such as the full-court press. A press is also a crowd or an acting of crowding together.
Pressure is the application of force. As a verb, pressure means “apply force,” and the verb pressurize refers to injecting a gas into a container in a greater concentration than outside the container (or pertains to designing the container for that purpose). The adjectival form is pressurized, and the act is pressurization. (The corresponding antonymic forms are depressurize and so on.) The adjective “high pressure” denotes a literal or figurative situation in which force is applied, often in the context of its effect on an individual, as when referring to a high-pressure job. Tension or pain resulting from such situations can be alleviated by acupressure, a therapeutic application of pressure to points of the body. (One form of acupressure, developed in Japan, is called shiatsu—literally, “finger pressure.”)
To compress is to push against or together, or to reduce as if by doing so, and something compressed undergoes compression. As a noun, it describes a piece of cloth applied to a body part, especially an injured one, as treatment, or pertains to a device that compresses; an example of the latter might, alternatively, be called a compressor, such as a machine that compresses air to provide force for a tool. To reverse compression is to decompress.
Depress, by contrast, means “push down.” By extension, word also came to apply to lowering someone’s spirits or reducing value. The adjective for all senses is depressive, and depression describes an act of depressing or a physical alteration of a landform or an object that leaves one area or part lower than the rest; the word also has astronomical, mathematical, and meteorological senses. (The historical period of economic distress that lasted roughly throughout the 1930s throughout the world is called the Depression or the Great Depression.)
Depressant is a synonym for sedative, and a medication intended to alleviate depression is an antidepressant.
Express means “expel” or “push out” (hence the borrowed Italian word espresso, which refers to coffee brewed with steam pressure), but it also came to mean “put into words” or “represent.” Something that can be expressed in the former senses is expressible, and the latter connotations are represented by the adjective expressive. (The antonyms are inexpressible and inexpressive.) The adverb expressly, however, means “plainly.” Something expressed is an expression, including an attitude or emotion signaled by the way one’s face is shaped by movement of one’s eyebrows, mouth, and so on. (Expressive also describes something that reveals attitudes and emotions.)
Express itself came to be employed as an adjective meaning “implied,” and both as an adjective and adverb, it refers to a special condition or treatment; for example, an express train is one that travels directly from one station to another, bypassing intermediate stops. In this sense, the word also serves as a noun, as when sending a package by a rapid delivery method. A system of doing so is called an express, and the word used to apply to a messenger employed to deliver something quickly. An expressway, meanwhile, is a thoroughfare with a minimum of exits or intersections.
Impress refers to having an emotional or physical effect or influence. Something that leaves a positive emotional impression because it is aesthetically pleasing or demonstrates achievement is impressive. An impression may be an effect or influence, an uncertain or unclear belief or idea, or an appearance or suggestion; the word also refers to an emotional or physical application, such as fixing a personality trait or stamping an object. (The use of press and impressment to refer to an act of forced labor or military service is unrelated; the source of these terms is the Latin verb praestare, meaning “stand before.”)
To oppress is to push against, to repress is to push back, and to suppress is to push down; the adjectival forms add -ive, and actions are indicated with the inflection -ion. All three terms often pertain to using despotic force against people agitating for freedom or rights. Repress and suppress also apply to excluding emotions or thoughts from one’s consciousness.
Oppress may also apply to an emotional or spiritual burden. One who, because of a buoyant or determined personality, seemingly cannot be repressed is described as being irrepressible, and a suppressant is a drug that controls or prevents a reaction or state.
Print (and imprint) are disguised relations of the press family, as is imprimatur; that word (New Latin for “let it be printed) originally applied to a printing or publishing license authorized by the Catholic Church, and later referred to approval to do so in general and then, by extension, pertained to any type of approval or a mark of approval.