Antisonante is not a typo. The word exists in Spanish.

Spanish term (edited): Me insultó con palabras altisonantes.

There clearly seems to be a typographical error here, as the word that makes sense in this context is "aLtisonantes."

Suerte.

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Note added at 2 hrs (2013-09-09 18:11:26 GMT)
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Assuming Vidomar and Jenni are right, and that "antisonantes" is not a typo, I would offer the following as a natural translation that might be heard coming out of the mouth of an adult American:

He insulted me with some pretty nasty language.

Or maybe "insulted me in vulgar terms" or "insulted me in strong language". It means profanity or swearing.

"Antisonantes" is not a real Spanish word. It's not exactly a typo; it's a word people use deliberately but incorrectly: a sort of malapropism. What they mean is "palabras altisonantes". This confusion is reflected in several yahoo questions, one of which Jenni has quoted.

As any dictionary will tell you, "altisonante" (or "altísono") means "high-flown", as Robert puts it: pompous, flowery language. However, in Mexico it has undergone a curious semantic shift and can also mean vulgar or profane: "palabras altisonantes" means profanity, swear words.

I can't say how this shift occurred. Perhaps the idea is of language that is "over the top", exaggerated. The answerer in the yahoo question Jenni quoted said ""altisonante" se refiere a palabras que "suenan" mucho por su contenido polémico o vulgar"
http://es.answers.yahoo.com/question/index?qid=2008062212432...

But it is a curious shift, and perhaps this gives some people the sense that "altisonante" is not the right word, leading to the invention of a more negative-sounding alternative, "antisonantes".

I first came across this meaning of "altisonante" in the Spanish Wikipedia on "lenguaje soez", where there is an interesting list of expressions for swear words in different Spanish-speaking countries. It includes:

"lenguaje altisonante (en México)"
http://es.wikipedia.org/wiki/Lenguaje_soez

And it's confirmed by this Mexican academic article entitled "“El léxico de los estudiantes universitarios a partir de las 'expresiones altisonantes’ como corpus cultural y representacional”", where it quite clearly means specifically swear words or profanity:

"También se ha encontrado que en diversas sociedades las palabras altisonantes, aunque son consideradas como agresivas, insultantes, o inapropiadas por los miembros de la misma, es frecuente que en ciertos contextos sean muy usadas y no siempre rechazadas, hasta el grado de considerarlas graciosas o parte de la jerga cotidiana en las conversaciones informales, incluso pueden tener un prestigio encubierto entre ciertos grupos sociales.
Otra aportación interesante del estudio para la explicación sociolingüística de las “palabrotas” es que el lenguaje soez generalmente es utilizado para expresar de manera insultante referencias a lo sagrado, como la religión y las relaciones familiares, o acerca de lo que se considera tabú, como el sexo, las partes del cuerpo o las relaciones personales entre los seres humanos."
http://versatilsite.com/pdf/el lexico.pdf



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Note added at 15 hrs (2013-09-10 06:38:59 GMT)
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What I do think is that the specific meaning of "antisonante" (= "altisonante") should be reflected in the translation. It's one thing to insult people, but another to use profanity/swear words in doing so; that is crossing a line, and if this is about an employment complaint (reporting a conversation at work), the distinction could be important.

aggressive/pedantic/pompous/petulant/

… anti-sonante quiere decir contra-sonante, lo cual está mal dicho, en cambio alti-sonante quiere decir que suena alto, es decir, que las groserías suenan alto.

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Note added at 1 day6 hrs (2013-09-10 22:08:01 GMT)
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aggressive