Year in, year out Definition 1 of 1Pro Tip 1/3Unchanging Routine Expresses something done with such regularity it becomes a fixed part of life, without change. He goes jogging at 6 am, year in, year out. Pro Tip 2/3Not Just Holidays 'Year in, year out' isn't limited to annual events but includes regular occurrences. She has attended the book club meetings, year in, year out. Pro Tip 3/3Emotional Implication Can imply a sense of monotony or steadfastness depending on the context. The couple celebrated their anniversary the same way, year in, year out.