slang An abbreviation of "same old same old," referring to the same thing that is always done or that always happens, especially when it is boring or monotonous. The abbreviation is almost exclusively used in writing, so as not to be confused with the term "so-so" (meaning "average or mediocre"). A: "Hey, how's your visit with your parents?" B: "SOSO. Mom and Dad are the same as ever." I was told this would be a dynamic, shifting job, but so far it's been nothing but the SOSO.