Jenny Afia, speaking during a BBC podcast, said the duchess denied the claims but she did not “want to negate anyone’s personal experiences”.
Ms Afia, head of legal at law firm Schillings, told broadcaster Amol Rajan the term bullying gets used “very very casually” and was damaging for “career women”.
Jason Knauf, the Sussexes’ then communications secretary, made the bullying complaint in October 2018 in an apparent attempt to force Buckingham Palace to protect staff.
Mr Knauf reportedly sent an email outlining the duchess’s alleged actions to Simon Case, the Duke of Cambridge’s then private secretary and now the cabinet secretary, after conversations with Samantha Carruthers, the head of human resources.
Buckingham Palace launched an investigation into the claims last March, and invited past and present employees to speak in confidence about their experiences of working for Meghan, after it was alleged she drove out two personal assistants and staff were “humiliated” on several occasions.
When asked if Meghan bullied staff, Ms Afia told the podcast series Harry, Meghan and the Media: “No, absolutely not. And I think first thing is to be really clear about what bullying is.
“So the term gets used very, very casually. My daughter called me a bully last week when I asked her to brush her teeth – she’s seven years old.
“So the term is used very freely, and it’s a very very damaging term as we know, particularly I think, for career women.
“What bullying actually means is improperly using power repeatedly and deliberately to hurt someone, physically or emotionally.
“The Duchess of Sussex absolutely denies ever doing that. Knowing her as I do, I can’t believe she would ever do that. I wasn’t there at the time, but it just doesn’t match my experience of her at all and I’ve seen her (at) very, very stressful times.
“So that story is absolutely untrue that she is a bully – that said, she wouldn’t want to negate anyone’s personal experiences.”
Details of the investigation into the bullying claims were expected to be included in the annual royal financial report released last summer, but were not.
A source has said the cost of the ongoing independent inquiry by a law firm is being met privately, and it is likely a senior member of the royal family is paying the bill, but it is unclear when or if the privately-funded report will be published.