Patrice Evra has been informed that he may have difficulty proving he was the victim of racial abuse from Luis Suárez, because of a counter-argument that certain variations of the N-word are not deemed offensive where the Liverpool player grew up, in Uruguay.

The Manchester United defender has accused Suárez of using racist language during a 1-1 draw at Anfield on 15 October and is waiting to discover whether, almost a month later, the Football Association will charge the Liverpool striker with misconduct. Top-level sources at Old Trafford say the offending word was uttered in Spanish and allegedly was a derivative of "negro", with Evra stating that it was used "at least 10 times".

However, Suárez has categorically denied racially abusing the Senegal‑born France player and the FA's investigators are having to consider the different context with which words that would be considered offensive in England are commonly used in Uruguay and other Spanish-speaking countries.

"Negrito", for example, could have shocking connotations for someone without full knowledge of the nuances of the language. But the counter-argument is that this is one of several derivations that are used in many countries, with no derogatory meaning – often in the same way someone could be called "pal" or "

mate". An illustration of this comes in the form of the message Dani Pacheco, the Liverpool player who is currently on loan at Rayo Vallecano, sent to his Spain Under-21 team-mate Thiago Alcântara via Twitter on Friday. It begins: "Negrito, enjoy yourself …"

This was a conversation between two friends. In Uruguay, it is quite common for commentators to use the same word to describe Premier League players. Visitors to the country can be taken aback by this form of language. But other derivatives are also commonly used, often to describe people of all races in affectionate terms, including family members.

Whether Evra was aware of these nuances at the time is not clear, but he and United have subsequently been informed that the case does not merely rest on what Suárez said but also, crucially, the context in which his words were used. The two players were arguing at the time and it is beyond argument that Suárez was trying to wind up his opponent, but the crux of the matter is the meaning of whatever was said and differentiating between something that would not be offensive in one country but shocking in another.

Suárez, backed by Liverpool, has repeatedly protested his innocence. The forward, who scored all four goals as Uruguay beat Chile 4-0 on Friday, has not publicly disclosed the words he used. He said last week that it was not an insult but just a "way of expressing myself. I called him something his team-mates at Manchester call him, and even they were surprised by his reaction."

The complexities of a difficult, highly sensitive case help to explain why the FA has taken so long to decide whether to take action against Suárez. The player's poor grasp of English has also contributed, as all his interviews have been in Spanish, requiring careful translation.

Any case against him would also have to prove that, having played in Europe since 2006, he should be aware of what is acceptable or not. However, this would be a difficult task. If Suárez accepts he used one of the N‑words, he would have the scope to argue it is a common and inoffensive term for someone of his background, citing a clash of language and culture between one player from South America and Europe.

Liverpool have let it be known they will ask the FA to take action against Evra if the governing body concludes that Suárez has no case to answer. However, the latest revelations throw up the possibility that both players have given a legitimate account of what happened, rather than it being a case of one man's word against another.

Kenny Dalglish, the Liverpool manager, has voiced his objections about the length of time the case is taking the FA, but it is still not clear when an announcement will be made. The case is so complex it may be that the FA needs to take advice from South America about the relevant linguistic issues before deciding whether or not to proceed any further.