Nicole Kidman has a legion of loyal supporters and her husband, Keith Urban, is certainly one of them. 

The Big Little Lies actress received the sweetest message from the country singer on Instagram and in it, he revealed his nickname for his wife. 

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Keith was incredibly proud to congratulate Nicole on her Golden Globe and SAG nominations and wrote, alongside a photo of her: "Congrats babygirl on the tip top of the hats from the @goldenglobes and @sagawards for your 'skills on fire' performance in @undoinghbo!!!!!"

WATCH: Nicole Kidman and her daughters surprise Keith Urban 

It's not just Nicole who has an alternative name of endearment, as she also has a quirky moniker for him!

In a recent interview, she revealed she calls him her, "mellow muso". Muso is Australian slang for musician and she explained to MSJ. Magazine: "He’s pretty much the flip side of neurotic."

And it doesn't stop there. When he's not calling her 'baby girl' he has another romantic name for her… Hokulani.

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READ: Nicole Kidman's children following in her footsteps - all we know

Keith congratulated his 'baby girl'

Nicole told Instyle that it was the name her parents gave her when she was born on the Hawaiian island of Oahu. 

"My mum called me Hokulani. It means heavenly star," she explained. "That's something no one really knows. Well, Keith knows it. He calls me Hokulani sometimes."

The adorable couple will celebrate their 15th wedding anniversary this year and are proud parents to the two daughters they share, Sunday, 12, and Faith, ten.

MORE: Nicole Kidman's son Connor sparks reaction with rare personal photo

SEE: Nicole Kidman's daughter Bella quizzed by fans over unusual art piece

Nicole and Keith have sweet nicknames for one another 

Keith confessed the secret to their marriage is maintenance.

"It's tending to the garden," he told Woman's Day. "If you don't do the work, the garden starts to grow over, and then you complain that the garden is not very interesting and you look for another garden. I maintain this garden."

He added: 'Nicole is also my best friend. I've never had anyone on the planet who knows me as well as she does."

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