Learn English – What does the expression “If + subject + was/were + infinitive” mean in American English

When the English settlers landed in the New World, they didn't have a word for maize. Maize is a New World crop which was unknown in Europe. The word "maize" was originally Spanish, and comes from the word "mahiz" in the Arawak language of Haiti, and in the early 1600s it was not yet a common word in England. The settlers called it "Indian corn", which soon got shortened to just "corn".

EDIT: In the comments, some people are questioning whether "Indian corn" and "maize" refer to the same thing. They certainly don't today; in the U.S. Indian corn usually means ears of maize with multicolored kernels which are grown primarily for decoration. However, both terms were used and appear to have been treated as synonyms in the U.S. during and before the 18th century. From a section of An Universal History (London, 1763) discussing New England:

We have already observed that the country is fruitful in all kinds of esculent plants, pulse, and corn; but Indian corn, or maiz, which the natives call Weachin, is the most cultivated, and was alone known here on the first arrival of the Europeans. The following is the account of it communicated to the royal society by Mr. Winstrop ... "The ear is a span long, composed of eight or more rows of grain, according to the quality of the soil, and about thirty grains in each row, so that each ear at a medium produces about two hundred and forty grains, which is an astonishing increase. It is of various colours, red, white, yellow, black, green, &c, and the diversity frequently appears not only in the same field, but in the very same ear of corn, though yellow and white be the most common. ... It is observable, that the maize dwindles the farther you advance to the northward ... sufficiently evince the Indian corn to be a native of the more southern latitudes ... "

The earliest reference in OED is from 1598, from John Florio's Italian/English dictionary A worlde of wordes:

Cacafuoco, a hot violent fellow, a shite-fire.

We can say that the term was coined by J.Florio. The books An Encyclopedia of Swearing (by Geoffrey Hughes) and Joy of Swearing (by M. Hunt, Alison Maloney) support this claim also.

John Florio was born in London and he was of Anglo-Italian origin. Thus, the word shitfire is of British origin.

Interesting note: Cacafuego is a rarely used loan-word in English also and there is an entry of the word in OED where it is defined as:

A spitfire; a braggart.
   _{(The name of the Spanish galleon taken by Drake in 1577.)}

Here is the etymology from OED:

< Latin cacāre, Spanish cagar, Portuguese cagar to discharge excrement + Spanish fuego (Portuguese fogo) fire < Latin focus hearth.