Boris Johnson was branded a "muckle glaikit numpty" by an SNP activist leading a debate on the Scots language at the party's conference.
Jack Capener said as many as one in three people identified as speaking Scots.
And he told the gathering in Aberdeen: "If you consider Boris Johnson a muckle glaikit numpty ye ken some Scots."
Muckle means large, big or a great size, according to the Dictionary of the Scottish Language, while glaikit translates as stupid, foolish; thoughtless, irresponsible, and a numpty is a stupid person or idiot.
He spoke as the conference passed a resolution calling on the Scottish Government to support the promotion of the Scots language "as part of celebrating Scotland's linguistic diversity".
Capener told the conference action was needed, saying: "Despite the language being everywhere, it is also nowhere at the same time, because officially it barely exists.
"There's no legislation protecting it, there's no national strategy to promote it, and it has no official status. It is absent from broadcasting, school curriculums and from our national conversations.
"We need political action to change this."
He also called for a Scots Language Board to be set up to work with public bodies and businesses to raise awareness of the language.
Why are you making commenting on The National only available to subscribers?
We know there are thousands of National readers who want to debate, argue and go back and forth in the comments section of our stories. We’ve got the most informed readers in Scotland, asking each other the big questions about the future of our country.
Unfortunately, though, these important debates are being spoiled by a vocal minority of trolls who aren’t really interested in the issues, try to derail the conversations, register under fake names, and post vile abuse.
So that’s why we’ve decided to make the ability to comment only available to our paying subscribers. That way, all the trolls who post abuse on our website will have to pay if they want to join the debate – and risk a permanent ban from the account that they subscribe with.
The conversation will go back to what it should be about – people who care passionately about the issues, but disagree constructively on what we should do about them. Let’s get that debate started!
Callum Baird, Editor of The National
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereLast Updated:
Report this comment Cancel