Penny-farthing, high wheel, high wheeler, and ordinary are all terms used to describe a type of bicycle with a large front wheel and a much smaller rear wheel. Although they are now most commonly known as "penny-farthings", this term was probably not used until they were nearly outdated. It comes from the British penny and farthing coins, one much larger than the other, so that the side view resembles a penny leading a farthing.
What's up with the big wheel?
In about 1870, James Starley, described as the father of the bicycle industry, and others began producing bicycles based on the French boneshaker but with front wheels of increasing size, because larger front wheels enabled higher speeds on bicycles limited to direct drive.