Definition of rundown
In French, we could translate rundown per ascending. But let's say that the use of the word "montante" is quite marginal. A rundown is, on the Omaha, the succession of 4 cards that follow each other. If in your 4 hidden cards you receive 2-3-4-5 or 5-6-7-8 you have a rundown. You can have rundown offsuit, single suited or double suited. For example, 2-3-4-5 with 4 different colors is a rundown offsuit (mismatched). If you have say 2 spades among your 4 cards, you will get a rundown suited (matching in French) and if you have 2 spades and 2 clubs say, you will get a rundown double suited (DS) for double matching.
How strong is a rundown?
A rundown is a relatively strong hand. Obviously, the higher your rundown is, the stronger it will be. And if you have a double matching rundown, it will be even stronger. The reason for the strength of these hands is that they connect very well with many paintings. Let's imagine a rundown as 4-5-6-7 on a 6-7-2 flop. We only have two pairs, but in addition you have a straight draw. And if the board is more like A-K-J, those hands will be easy to play; all you have to do is fold, of course.