A person of minor significance, accomplishment or acclaim; a common and undistinguished person.
"After years of chasing fame as an aspiring actor, he finally settled for being just another mediocre extra in the background."
moderate to inferior in quality
"they improved the quality from mediocre to above average"
Having no peculiar or outstanding features; not extraordinary, special, exceptional, or great; of medium quality, almost always with a negative connotation.
"The movie was so mediocre that I felt like leaving halfway through because it lacked any interesting plot twists or memorable characters."