When I started looking into my family's history and came across Clan Scott, I thought it interesting that the Chief of a Borders Clan that was rather aggressive towards their neighbors (English and Scottish alike) would choose the Latin 'Amo' - 'I Love' - as his motto.

Since it would be difficult at best to find the original grant of arms (I don't know when the original grant of arms was done, or to whom, and it's not likely to include explanation of the choice at any rate), I prefer to think - and have suggested to others - that instead the motto may be the Scots word meaning 'among', or 'in the middle of', since one of the Scotts of Buccleuch (the chiefly line) was the Sheriff of the Middle March at one time. Also, the language of the Scottish royal court was Scots for a time, so it makes some sense (to me at least) that some grants were made with Scots mottoes.

That said, I appreciate the OP's offer of providing a translation upon request. Very kind indeed.