The IAAF's medical commission, which begins meeting Friday, could take a year to deliver that definition and the judicial commission will also be asked to consider future regulations, general secretary Pierre Weiss said Saturday.
"We are obliged to react. It would have been better if we had been prepared to, but we were not prepared," Weiss told The Associated Press on Saturday. "We will get a reply in the next 12 months _ I don't expect anything to come out before. ...
"We were in Copenhagen (at the International Olympic Committee meetings) and I asked my colleagues from other sports if they had a definition and nobody has one. But nobody (else) has had the problem so far."
Weiss expects the IOC medical commission to also consider the issue in November in Lausanne.
The most common cause of sexual ambiguity is congenital adrenal hyperplasia, an endocrine disorder in which the adrenal glands produce abnormally high levels of hormones.
By the time Semenya won the 800 meters at the Berlin world championships in August, questions about the 18-year-old South African's gender had been raised because of stunning improvements in her times and her muscular build and deep voice.
Before the final, the IAAF announced it had ordered gender tests.
The IAAF has refused to confirm or deny Australian media reports that Semenya has both male and female characteristics. It says it is reviewing test results and will issue a decision in November on whether she will be allowed to compete in women's events.
"They are being analyzed worldwide by experts," Weiss said. "We will promote the outcome of this case as soon as it is known."