Isn't age just a number? Well, apparently not in Hollywood. 

In an interview with the Howard Stern Show Tuesday, actress Olivia Wilde said she experienced age discrimination first hand when she was denied the role of Leonardo DiCaprio's leading lady in the "Wolf of Wall Street" for apparently being "too old," USA Today reports.

The 32-year-old was up for the role as DiCaprio's wife in the critically acclaimed movie, but was turned down for the part because of her age, despite being 9 years younger than the 41-year-old DiCaprio, according to Sommeecards. 

"I had heard for a part that I was too sophisticated," Wilde told the Howard Stern Show. "I was like, 'oh, that sounds nice. I like that feedback.' I didn't get the part, but I'm a very sophisticated person. And then I found out later that they actually said 'old.' I want to make a translation sheet for Hollywood that's all the feedback your agents give you and what it really means."

Wilde eventually lost the role to 25-year-old actress Margot Robbie, who was 23 at the time of the film's release in 2013. Despite the missed opportunity, Wilde said she doesn't hold any resentment. In fact, she praised Robbie on Twitter for a job well done.

And eventually, Wilde nabbed her "dream job" acting role.

Ageism is a serious problem in Hollywood, especially for women.

Forty-six-year-old actress Catherine Zeta-Jones called out Hollywood for its treatment of its more "mature" actresses as another component to the #OscarsSoWhite diversity campaign earlier this year, according to the Huffington Post.

"I have been in this business since I was nine years old, and have heard the same thing said throughout the different parts of my career," Zeta-Jones told the Guardian. "Then, HELLO, I’m in my 40s ... and it’s true. It’s not that there aren’t great stories to be told about women in their 40s, its just that the big bosses in Hollywood feel that the demographic of moviegoers are less interested."

In 2015, actress Maggie Gyllenhaal was taken aback when she was told that she could not play the love interest of a man 18 years her senior. 

"There are things that are really disappointing about being an actress in Hollywood that surprise me all the time," Gyllenhaal told TheWrap magazine. "I’m 37 and I was told recently I was too old to play the lover of a man who was 55. It was astonishing to me. It made me feel bad, and then it made me feel angry, and then it made me laugh."

Actress Liv Tyler also expressed her frustration with Hollywood's ageism when she stated the she felt like a "second-class citizen" as she approached her 40s, the Guardian reports. 

According to study reported by Variety, female actresses are generally younger than their male peers. The majority of female characters are in their 20s and 30s whereas 53 percent of male characters are more than 40 years old.