Phrase used when advising somebody of facts /an issue /and explanation (etc) using the most simplest of words in order that they may understand.
Often associated with 'full and frank conversation' the phrase 'words of one syllable or less' is actually gramatically incorrect in its use of 'or less' (essentially 'or less' makes no sense whereas 'or fewer' would be correct) but nicely conveys the situation.
Believed to have originated with the staff of Britain's railways in Southern England.
"What do you mean Bert has done it wrong again?
I'd better go and explain how to do it in words of one syllable or less"
Polite term used within the UK railway industry for giving someone (usually but not exclusively another member of staff) a severe reprimand or right bollocking for something they had done wrong, even dangerous or that they had allowed to happen.
A full and frank discussion may occur in lieu of a more formal reprimand such as a Form One offence.
Term is frowned upon within modern safety critical communications. Example being - shunter to driver "the signalman will give you the dummy in a minute" meaning the signal man will clear signal no. (XYZ) in a minute thus allowing the train to proceed.
Term coined by the Southern Region of British Rail (UK) in the 1980's as an abreviation for "Daft As Arseholes which in terms refers to gricers, cranks and those at the extreme end of railway enthusiasts.
DAA special aka crankex - a railtour orientated at enthusiasts wanting to travel on a particular, perhaps unusual railway route and /or with odd traction compared to a more traditional day-out excursion.