What is another word for isn't?

Answer 1

"isn't" is a contraction of the words "is not". For the most part you can use the contraction (in place of the two words) in less informal writing to more closely emulate spoken conversation.

Examples:

It isn't fair he got a bigger piece of cake!

{Very informal (conversational style), although "is not" could be used in its place.}

As in, "It's NOT fair he got a bigger piece of cake!" {Notice the contraction of "it is" to "it's".}

versus

The defendant claimed he is not responsible for the damage.

{A more formal written style that typically precludes the use of contractions, such as "isn't", "it's" or "they're", except as part of a direct quotation.}

Answer 2

is not

Answer 3

aren't