I heard a woman on the radio the other day say she was swithering, when asked about who she was going to vote for in the forthcoming general election. The Radio 4 Today programme presenter Jim Naughtie used the word swithering too. They were both Scottish, and the verb to swither is a Scottish word. It means to dither or be undecided. According to this article, it is such a common word in Scotland that Scots are often surprised to find that those of us south of the border don’t know it.
The article cites former MP and MSP Winnie Ewing who said swither in the House of Commons: "The members all stopped and said, 'I don't understand'. I wondered what the English word for 'swither' was, and they shouted, 'prevaricate' and 'hesitate'. Neither of those words is exactly the same as 'swither' ...” The word swither may also include the idea that the speaker is in a state of nervous agitation and can indicate that there is fitful movement involved. The Dictionary of the Scots Language records a number of instances of swithering cloud formations and unstable markets.
The OED is unsure of the origin of swither and states that any connection with similar Old English words cannot be assumed with certainty.