The word "complicate" is correct and usable in written English.
You can use it to describe a situation or activity that is complex, intricate, or hard to understand. Example sentence: The situation quickly became complicated and required careful consideration.
The Serbs have stalled, playing for time or one side off against the other, with Brussels warning them that a green light would complicate the EU negotiations.
And these deep and painful cuts further complicate the task of the British Film Commission (a division of Film London) "to promote the UK as the best place to produce feature films".
To complicate things, there are laws governing broadcasters and fair coverage during elections.
US Secretary of State John Kerry called his Russian counterpart Sergei Lavrov to object to the move, and the US government warned that the delivery could complicate plans to eventually lift sanctions on Iran as part of a deal over the country's nuclear programme.
But this week's Ashcroft poll suggests that the parliamentary arithmetic could be even more difficult this time, which would complicate matters for the palace.
And, besides, didn't he complicate the benefits system by forcing tax credits on anyone who would vote Labour?
The vagaries of running a top-flight football club were always going to complicate Tottenham Hotspur's mission to cut 10% of its carbon emissions.
To further complicate the picture, NHS Direct has already said it will compete to provide the nationally specified but locally commissioned NHS 111 urgent care services.
For Serbia, the ruling could complicate the balance of its awkward politics.
Or for those who see sexism everywhere to refuse to discuss it in any other way, as though to do so would complicate the issue.
But Ukip and the BNP had a strong presence in the two seats in 2010, and could complicate the picture.
