Does “vehicle” usually include airplanes, aircrafts or spacecrafts? Or it mainly refers to wheeled vehicles, boats and ships?

The words mainly and usually are rather troublesome words in your question.

The meaning of vehicle – much like the meaning of any word with multiple definitions or interpretations – depends on the context. If I said, “It costs a lot to register a vehicle in Kentucky,” chances are I’m only referring to cars, pickup trucks, and motorcycles. However, if I work as a logistician for a major company, and I say, “We need to determine the best vehicles for getting these widgets from factory to market,” chances are I am referring ships, trains, large trucks, or aircraft. And if I talk about needing a vehicle to put a satellite into orbit, I don’t mean any of those things.

If I heard the word with no other context, as in a word association game, chances are I would initially think of motor vehicle, which would make me think of car first, then perhaps other similar vehicles, such as trucks and motorcycles, but that wouldn’t preclude the word from being used in other ways.

Also, I’m not sure the logistician would use the word vehicle; words like conveyance might be more common in that context.

This Ngram might lead one to conclude that the word vehicle “mainly” refers to wheeled vehicles: that is, cars and trucks. Personally, I’m not comfortable with saying that, because that makes it sound like other uses of the word are somehow odd, unusual, or less acceptable. Other uses of the word may be less common, but that’s hardly the same as unusual or awkward.

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