The noun hovercraft denotes a machine or craft that can be supported by a cushion of air ejected downwards against a surface close below it, and can in principle travel over any relatively smooth surface—such as a body of water, marshland or gently sloping land—while having no significant contact with it.

This noun occurs, for example, in Is a £16m giant magnet the ‘holy grail’ of clean energy?, about “ITER, a 23,000-tonne, 35-nation nuclear experiment under construction in France”, by Josh Marcus, published in The Independent (London, England) of Saturday 15^th January 2022:

Some parts of the solenoid are so heavy that they need to be moved across the shop floor on a hovercraft.

The following photograph showed the hovercraft in question:

Each 110-tonne module must be moved by a hovercraft-like transporter (General Atomics)

The noun hovercraft is from:
– the verb hover, meaning to remain suspended in the air;
– the noun craft, denoting a means of transport.

The earliest occurrences of the noun hovercraft that I have found are as follows, in chronological order—it seems that, in British-English use, this noun was coined (together with hoverplane) by the inventor of the hovercraft, the British engineer Christopher Sydney Cockerell (1910-1999):

1-: From The Arizona Daily Star (Tucson, Arizona, USA) of Wednesday 14^th May 1958—however, here, hovercraft denotes “a flying car”:

Advertising Frat Pushes Its ‘Hovercraft’

In the year 1970 the Tucson businessman may be living far from the city’s noise, somewhere beyond the mountains that surround our mesa; yet he will be at work on time every morning. He will merely get into his “Commuter Two,” drive to the nearest takeoff spot, fly into Tucson and land on the roof of his office or store building.
This is the way the members of Alpha Delta Sigma, advertising fraternity at the University of Arizona, have it set up with their brand new mythical creation, a flying car. “Get out of the crowds and into the clouds” is the slogan they dreamed up to put this new machine before the buying public. Their advertising campaign will be entered in the national ADS contest.
Last year the local chapter of the fraternity won second in the national contest, and in 1956 it won first. The entry must be an advertising campaign for a completely new product. Last year the chapter advertised suntan pills which are now a reality. This year its creation is a “Hovercraft.”

2-: From The Daily Telegraph and Morning Post (London, England) of Saturday 24^th May 1958:

BOAT BUILDER INVENTED THE “HOVERCRAFT”
CUSHION FLIGHT
By AN AIR CORRESPONDENT

The inventor who has discovered a revolutionary method of sustaining a weight in the air with comparatively little power is a Suffolk boat builder, Mr. C. S. Cockerell, I can now reveal.
His discovery, although still in its early stages, promises to provide an entirely new means of transport which will be almost frictionless.
The invention has been named the “Hovercraft.” Mr. Cockerell has approached a number of firms about it, but the first authoritative recognition of it was taken by officials in the Ministry of Supply.
The National Research and Development Corporation has since become closely interested. So far, however, the only money invested in it has been provided by Mr. Cockerell.
For some years Mr. Cockerell has worked on similar lines to other inventors in Britain and America to evolve a method of providing a “cushion” of air beneath an object which would suspend it and allow it to be moved without the friction of wheels running on road or rails or the friction of water on the hull of a ship.
At his home, by using a particular method, he has made a model powered by a small engine remain a few feet above the ground. The importance of the invention lies in the fact that the thrust from the engine need be less than the weight of the whole machine.
Helicopters and vertical lift jet planes like the Short S.C.1 require engines with a thrust greater than their weight. Mr. Cockerell’s invention employs a method of blowing air downwards to produce the “cushion.”
Piston engines, rather than jet engines, can be used to drive compressors supplying the air pressure.

3-: From the Sunday Dispatch (London, England) of Sunday 25^th May 1958:

My Flying Saucer
1,000 MAY RIDE ON A CUSHION OF AIR IN SPACE AGE ‘OCEAN LINER’
By RICHARD CAREY

BRITAIN’S Unknown Boffin, the man who has invented a “Flying Saucer” that will “sail” above the sea’s surface, came out of hiding yesterday. And he prophesied that within 18 months one of his “Hovercraft” would be launched with a man in it.
Ultimately he believes his invention can be adapted to power a giant ocean-liner size flying saucer, which would give Britain a phenomenal lead in world transport.
“The possibilities are tremendous,” he said. “So great, in fact, that I am frightened to say too much about them.”
[…]
“I have instructions from the Ministry of Supply not to say anything,” he said. “We already know the Americans are working on this idea. If anything leaks out before the patent is registered the hoverplane may be lost to Britain.”
What is the principle behind the hoverplane? “Simply,” said Mr. Cockerell, “to provide a ‘cushion’ of air beneath an object which will allow it to be moved without friction.”
In practice this would enable enormous weights to be lifted with comparatively little power.
Government-sponsored research is now being conducted by Saunders-Roe, one of Britain’s biggest aircraft firms, to find out if Mr. Cockerell’s secret can be adapted to build a “flying ship”—which might carry as many as 1,000 passengers, or huge loads of freight, quickly and cheaply.

The following photograph and caption are from The Sphere (London, England) of Saturday 15^th August 1959:

THE HOVERCRAFT SHOWS ITS PACES TO THE FRENCH: In the Channel near Calais the revolutionary machine leaves a great, white-flecked wake behind as it gives a demonstration before its Channel crossing. The white central air duct dominates the structure. At the sides of the machine are the horizontal air ducts which provide forward and backward movement as the craft rides on its air cushion about 18 ins. above water. Capable of speeds of up to 25 knots, it is powered by a 450 h.p. aircraft piston engine.