having no distinguishing marks or features.

without any claim to distinction

an undistinguished performance.

unnoticed; inconspicuous

He was an undistinguished part of the crowd.

not separated or divided, as by sets or categories.

adjective

average , characterless , common , commonplace , dull , everyday , fair , garden-variety , generic , mean , mediocre , modest , no great shakes , normal , nothing special , nothing to write home about , pedestrian , plain , prosaic , routine , run-of-the-mill * , second-rate , so-so * , typical , uneventful , unexceptional , unexciting , uninspired , unmemorable , unnoteworthy , unremarkable , usual , cut-and-dried , formulaic , garden , indifferent , run-of-the-mill , standard , stock , ordinary , unnotable