GROOVE

[noun] [C] - a long narrow hollow space cut into a surfaceThe window slides along a deep/shallow metal groove to open and close.To be in a groove means to do the same things for a long time and therefore to be boring.Things just go along in the same old groove.Don't get stuck in a groove, do something different.(figurative dated) Things are going well, we're in the groove (= everything is going successfully) now!