The Obama administration on Friday announced a significant expansion of the FBI’s definition of rape, which will now cover several forms of sexual assault and include male rape.

Justice Department officials said the revision would make reporting of the crime more accurate and provide a better understanding of its effects on victims.

Since 1929, rape has been defined as “the carnal knowledge of a female, forcibly and against her will.” That definition, which included only men having sex with women without their consent, excluded other forms of sexual assault, such as oral penetration and the rape of men.

The new wording, announced by Attorney General Eric H. Holder Jr., covers those and several other forms of sexual assault. It will be used in the FBI’s annual Uniform Crime Report, which draws on local police data, and probably will lead to an increase in reported rapes nationwide, law enforcement officials said.

Although most state rape statutes already contain a broader definition of the crime, officials said the federal revision holds deep significance because in the public mind, the FBI’s reports are often synonymous with crime rates. The FBI data are also used by policymakers to analyze crime and draft anti-crime initiatives.

Attorney General Eric Holder holds a news conference in Washington, Dec. 21, 2011. (BENJAMIN MYERS/REUTERS)

“This send a powerful message that . . . rape is rape,” said Susan B. Carbon of the Justice Department’s Office on Violence Against Women. in a conference call with reporters.“And it’s rape even if you’re a man. It’s rape even if you are raped with an object and even if you were too drunk to consent.”

Administration officials said that the change, which will take several years to fully implement, was driven primarily by Vice President Biden — author of the Violence Against Women Act when he was in the Senate — and the White House Council on Women and Girls.

Valerie Jarrett, a senior adviser to President Obama and the council’s chair, said the revised definition is “a major policy change that will lead to more-accurate reporting and a far more complete understanding of this devastating crime.”

An FBI police advisory board recently recommended the change, which had been pushed by supporters of women’s rights. FBI Director Robert S. Mueller III signed off on it last month.

In 2010, there were an estimated 84,767 rapes reported nationwide under the FBI’s current definition. Officials could not specify how much they expect the reporting of rapes to increase.

The new wording drew immediate praise from Sen. Patrick J. Leahy (D-Vt.), chairman of the Senate Judiciary Committee, and from advocates for women.

“All victims of these horrendous crimes deserve justice and should have access to the comprehensive services that will help them rebuild their lives,” Leahy said. “This updated, more inclusive, definition will bring added emphasis to sexual assault, which often goes unreported, and as a result, unprosecuted.”

Calling the change “a big win for women,” Eleanor Smeal, president of the Feminist Majority Foundation, said, “With a modern, broader definition, FBI Uniform Crime Report statistics will finally show the true breadth of this violence that affects so many women’s lives.”