Did an Americanism is a borrowed word whose form changed to make it resemble American English?

That's not entirely accurate. While some Americanisms may have their form changed to resemble American English, it's not the defining characteristic of an Americanism.

Here's a breakdown:

* Americanism: A word, phrase, or grammatical construction that is characteristic of American English. This can include:

* Words borrowed from other languages: These words may undergo changes in spelling, pronunciation, or meaning to fit into American English. For example, "soccer" comes from the British "association football," and "pajama" comes from the Hindi "payjama."

* Words created in America: This can be new words altogether or existing words with new meanings. For example, "OK," "cookie," and "blue jeans" are all American inventions.

* Different usage of existing words: Americans might use words in ways that are different from British English speakers. For example, "fall" for the season in America vs. "autumn" in Britain.

It's important to note:

* Not all Americanisms involve changes to a word's form: Many Americanisms are simply words or phrases that are more common in American English than in other varieties of English.

* Changes in form aren't always about making words "resemble" American English: They might reflect phonetic shifts, grammatical preferences, or cultural influences.

Therefore, while changes in form can occur, it's not the defining feature of an Americanism. The key is that the word or phrase is characteristic of American English.