At its most basic, an acronym is a word formed from the letters of the words it represents, generally the first letter of each word, but sometimes syllables or other parts of the word. Some acronyms have become so ubiquitous that they are no longer thought of as acronyms, but are more commonly used as words in and of themselves. These acronyms in particular primarily grew out of World War II and the mid-20th century generation.
RADAR
While the term started out as an acronym — standing for “RAdio Detection And Ranging,” “radar” is a technology used for many things, defined as “a system for detecting the presence, direction, distance and speed of aircraft, ships and other objects, by sending out pulses of high-frequency electromagnetic waves that are reflected off the object back to the source.” While the technology was developed over years by many scientists, Scottish physicist Robert Watson-Watt discovered its use for detecting enemy aircraft during WWII. While it’s still used in these sorts of military and detection contexts, it’s also now used more casually and metaphorically, as in, “Hey, I want to put this project on your radar.”
UFO
“UFO” stands for “Unidentified Flying Object,” and first emerged in 1953 amid the era’s space craze. The interest in potential alien visitors began a few years earlier, when, in the summer of 1947, a private pilot named Kenneth Arnold described seeing nine objects flying in close formation at a seemingly supernatural speed in Washington state. He described them as “flat like a pie and somewhat bat-shaped,” and that they “flew like a saucer would if you skipped across water.” From there, journalists began referring to them as flying saucers, which eventually became “UFO.” One important distinction: technically, “UFO” is an initialism rather than a strict acronym, since the letters themselves are pronounced rather than a whole new word.
CARE (Package)
Lucky summer campers and college students might receive a care package from mom when they are away from home for the first time. Colloquially, this is “a parcel of food, money, or luxury items sent to a loved one who is away.” However, the acronym comes from a program known as the Cooperative for American Remittances to Europe. The first CARE package arrived in Le Havre, France, in May 1946, beginning a wave of responses to millions in need of food and other supplies at the end of WWII. The CARE packages usually contained staples such as butter, dried milk, canned meat, and even chocolate or chewing gum.
SCUBA
You can’t get your SCUBA certification without learning what this acronym stands for. It means "Self-Contained Underwater Breathing Apparatus," which is a pretty straightforward description of the equipment and the activity. The term originated in 1952, and “scuba-diving” came around by 1956.
SWAK
“SWAK” is still defined as an acronym in the dictionary, meaning “sealed with a kiss.” During the war, soldiers and their sweethearts might write SWAK on the back of an envelope, perhaps even with a lipstick imprint. But as the war continued, soldiers and civilians came up with even more acronyms to express their love. Some were romantic (“OOLAAKOEW” meant “Oceans Of Love And A Kiss On Every Wave”), and some were more risqué (“CHINA” meant “Come Home, I’m Naked Already”).
SONAR
Similar to "radar," "SONAR" refers to a different type of ranging. Instead of radio detection, this one’s all about using sound to navigate — it stands for "Sound Navigation Ranging." It entered the language in 1946.