The feud between the two began when the caver criticized Musk's effort to help rescue members of a Thai soccer team from a flooded cave in 2018 - an event that drew the attention of worldwide media.
The Tesla CEO returns to the witness stand Wednesday after spending several hours at his defamation trial trying to dance around the meaning of the "pedo guy" tweet he aimed at Vernon Unsworth, a cave diver who helped rescue a dozen boys and their soccer coach from a flooded Thailand cave previous year.
Elon Musk's Twitter appears to be business as usual on the day he made a court appearance during a defamation case against him brought by Vernon Unsworth, who Musk called a "pedo guy" on Twitter.
Elon Musk has owned up to insulting a British spelunker in a rash tweet, but wouldn't concede on the witness stand that he called the man a pedophile.
The 48-year-old billionaire even apologised to the plaintiff from the witness stand in the Los Angeles court.
He added that Musk felt compelled to write the tweets as he was hurt by the suggestion that he was seeking publicity when he offered to help in the cave rescue.
"It just means creepy old dude, " Musk testified.
The tech inventor's attorney, Alex Spiro, has repeatedly labeled the British diver as an opportunist and said the insults were simply "an argument between two men".
"Just as I thought it was obvious that he did not mean to physically sodomize me with a submarine, I thought it was obvious that I didn't mean he was a pedophile", Musk said.
When Wood asked Musk whether he should choose his words carefully, Musk replied, "There are a lot of things I say, and not all of them have the same quality of thought. not everything can be thoughtful".
Musk's "pedo guy" tweet is one of three tweets that Unsworth has said defamed him and harmed his reputation.
To Spiro, Unsworth's interview represented an "attack" on the "genuineness of his efforts".
Moreover, lawyers for Unsworth argue that Musk doubled down on the accusation - emailing a BuzzFeed News reporter and claiming Unsworth has a "child bride", among other allegations, according to Unsworth's lawyers.
Unsworth's lawyers laughed off that explanation, saying Musk responded to a question on Twitter about whether he had accused Unsworth of being a pedophile with another tweet that said, "Bet ya a signed dollar it's true". "So, I insulted him back".
In a filing as part of a failed request to have the case thrown out of court Mr Musk had suggested that in South Africa, where he grew up, the term "pedo guy" is a common insult meaning "creepy old man" and does not accuse someone of paedophilia.
He's looking for unspecified damages for ache, struggling and emotional misery.
While the case does not involve Tesla, it is among the last issues hanging over Musk from a turbulent 2018 and early 2019, when he regularly clashed with Wall Street and short sellers as Tesla struggled with production problems. "It was a joking, deleted, apologized-for, responsive tweet".
Musk and Tesla reached a $40 million settlement with the Securities and Exchange Commission past year over allegations he misled investors with a tweet declaring he had secured financing to buy out the electric vehicle maker.
The trial, which began Tuesday, is expected to last about five days.
The lawsuit is not the first time Musk's tweets have landed him in hot water. Musk's lawyer will look to classify the use of "pedo guy" as an insult or opinion, not a statement of fact.
Musk said he posted his tweets without knowing what role Unsworth played in the rescue.