The word "jeep" was actually General Purpose vehicle in WW2 I think it was 2. So the vehicle was called a GP later became Jeep. They became so popular as a civilian vehicle when soldiers returning from war needed a vehicle to use on their farms so they bought old surplus GP's. The wave was also from this time, when soldiers would wave to each other when passing. That's about all I know, sorry I couldn't give you more. I'll look some more though.
Here's what I just found, sorry it's so long.
By 1939 the US military needed a new, universal vehicle to replace the motorcycle and its other vehicles (such as the modified Ford Model-T), so they invited 135 different car companies to compete for a contract to build a new vehicle for the military. The vehicle had to meet certain specs, such as a payload capacity of 600lbs, a wheelbase under 75 inches, a fold-down windshield, a gross vehicle weight of under 1200lbs, and it must be four-wheel drive. Only three companies entered, Bantam, Willy-Overland, and Ford.
Bantam enlisted the help of Karl Probst, and in 1940 was the first to produce a working prototype for the military, dubbed the Bantam Blitzbuggy and "Old Number One". Willy's-Overland and Ford soon followed with their own prototypes, the Willys Quad and the Ford Pygmy, which were basically knock-offs of the Bantam car. Willys eventually won the contract because of their 60hp "Go-Devil" engine, but Ford was also given a contract to help keep up with the military's demand for the vehicles for use in WWII. Willys later renamed their jeeps the MA and the MB, while Ford called theirs the GP and GPW. Many believe, as I do, that the Jeep won the war for the Allies.
As for the name 'Jeep', no one really knows for sure where it came from. Some people believe that it evolved from the Ford 'GP' designation, which many think stood for 'general purpose', which is incorrect. The "G" was for Government and the "P" was the vehicle class (80" wheelbase 4x4 ¼ ton truck). Another possibility is that the name came from Popeye's magical sidekick named jeep, who could do almost anything. For a more in-depth look at the origins of the Jeep, click on over to The Jeep, a Real American Hero.
In 1942 Ford built a limited number of amphibious Jeeps, known as the Seep. This little vehicle was basically an MB with a boat tub on the bottom (with cutouts for the wheels) and a PTO propeller. Seeps were not the most seaworthy things in the world, but one highly modified Seep, called "Half-Safe," did manage cross the Atlantic in 1950 and then continued on to circumnavigate the globe.
The CJ series began back in 1945 with the CJ2A. The name CJ stands for "Civilian Jeep," a bit of trivia that is still argued over. Next came the CJ3A's, and the CJ3B's which were produced until 1968. These early Jeeps are commonly referred to as "flatfenders" because their front fenders were flat across the front, even with the grill. Yes, there was such a thing as a CJ-4, and in true Jeep form, there is only one, literally. There is only one 1951 CJ-4 prototype in existence, it's the "missing link" between the flatfendered CJ-2's and 3' and the round-fendered CJ-5.
The CJ-5 came about in 1954 as a civilian version of the military's M-38A1 which came out in 1952. The CJ-5 stayed in production for almost 30 years, longer than any other Jeep model, and was taken out of production in 1983. During the time of the CJ-5 there was also a military and civilian CJ-6 which had a 101" wheelbase and later a 104" wheelbase, but it had a limited predication and was later replaced by the CJ-7.
The CJ-7, one of the most popular of the Jeeps, started its 10 year run in 1976. The CJ-7 has a longer wheelbase than the CJ-5 to accommodate an optional automatic transmission. Between 1981 and 1986 Jeep made a long-wheel based CJ-8 called the Scrambler, which was basically a pick-up truck version of the CJ-7. In 1987 the CJ-7 was replaced with the square headlighted YJ, more commonly known as the Wrangler. Like its predecessor, the Wrangler was redesigned after 10 years. The new Wrangler (now called the TJ) features the classic and much loved round headlights, dual airbags, a redesigned "90's interior", and an all-new Quadra-Coil suspension instead of leaf-springs. Interesting how much TJ sounds like CJ... The TJ got some minor upgrades and redesigns in 2003, including the much-anticipated Rubicon edition which features D44 axles front and rear with manual air lockers, a NV241J "RockTrac" transfercase with a 4:1 low range, rear disc brakes, and diamond plate rocker guards. Another addition to the TJ line was a new 4-sp automatic transmission to replace the previous 3-sp model.
2004 saw the introduction of the Jeep Wrangler Unlimited (LJ). The LJ is based off the TJ platform, but features a 104" wheelbase for increased cargo room. Standard features on the LJ include the 4.0L I6 motor and a D44 rear axle. The LJ also came with either the new 4-sp automatic, or a new-for-2005 6-speed manual transmission. The new 6-sp manual tranny is also available on the regular TJ's. In 2005 Jeep added a Rubicon edition of the LJ as well as an "upscale" Limited model with a chrome grill.
In 1956 Jeep began making the 2WD Postal/Dispatch Jeep (DJ). The DJ-3A was the first Postal Jeep and was a flat fender Jeep similar to the CJ-3A, except it was two wheel drive. The DJ-3A was produced from 1956 until 1965. In 1965 the DJ-5, which is the postal Jeep most people are familiar with today, was introduced. Jeep also produced a long-wheelbased version from 1965 until 1968, called the DJ-6. The DJ-5 was made by Jeep into the early 70s and production was continued under AM General. The Postal Jeep Page has some great info on DJ's.
From 1948 to 1950 Willys produced a 2-door "car" version of the Jeep, called the Willys "VJ" Jeepster. These were really cool looking cars, but with only 72hp, 2WD, and not much publicity, they didn't sell well...too bad.
In 1966, Jeep, now owned by Kaiser, debuted the Jeepster Commando to compete with the Bronco and Land Cruiser. The Jeepster Commando was available in three models: a convertible, pickup truck, and as a wagon (like the Jeepster, this was a really cool looking vehicle in my opinion). The (Kaiser) Jeepster Commando stayed in production until 1969. In 1970 AMC bought Jeep from Kaiser, and then in 1972 AMC shortened the name to just Commando and changed the grill design to look more like that of a Bronco, but it didn't catch on. The Jeep Commando was taken out of production in 1973. Check out The American Jeepster Club for more on these cool Jeep spin-offs.
In 1946 Willys began making the Willys Wagon and in 1947 came out with the Willys Pickup The wagon was available as a station wagon and also as a panel-side delivery truck. Both the wagon and pickup truck were made until 1965.
Jeep debuted the FC-series trucks in 1956. These trucks featured a cab-over-engine design. The FC-150 came out first and had a 78" bed and an 81" wheelbase. The FC-170 came out in 1957 and had a 108" bed and a 103" wheelbase. The FC-170 was also available in a 1-ton dually model (the FC-170DRW) that had a 10' flatbed. Other bodies were available for the FC-170DRW, such as dumptrucks and fire-engines. The FC trucks remained in production until 1964.