The Take That star welcomed his first child Theodora 'Teddy' Rose with wife Ayda Field last week.
Fans are said to have debated over the choice of the singer's baby name, with a popular theory being a link with early 20th century president Theodore 'Teddy' Roosevelt.
However, Williams has allegedly rubbished the rumours, stating that the couple simply like the name Theodora, reports The Sun.
He reportedly told a friend: "All this stuff is utter nonsense - I'm sick of the gossip.
"She's called Theodora just because me and the wife loved the traditional name. We also wanted to choose a name that could be shortened so we could use the abbreviated name as her middle one - hence Theodora 'Teddy'.
"The Rose part is nothing to do with us viewing her as some future English rose. We just thought she looked like a lovely flower when we first saw her, so Rose it was."
Williams recently revealed that he and Field were glad their child was not born on a Wednesday.