Noodle rods are slow action, full flexing, lighter rods. One place they came into prominence is on the Great Lakes tributary steelhead fishery. Long flexible rods for for fishing sensitive floats. I believe it is an extension of English trotting where very fine floats are precisely weighted to detect subtle bites from various fish species. They have some application and popularity here among steelhead circles. However, generally, in BC coastal situations, with our larger presentations and fast, brawling rivers (by some comparison), the vast majority fish 10'6" or a 11'3" rod medium action rod. Traditional centerpin fishers favour a rod that flexes a bit deeper into the butt section, but that is a matter of preference. The term is also used more generally to describe a softer, slower action rod of any type. You might hear someone say " that's a real noodle" vs "that feels feels like pool cue".
That is my understanding of things...
Happy Thanksgiving everyone
Hammer