outstanding
1 celebrated, distinguished, eminent, excellent, exceptional, great, important, impressive, meritorious, pre-eminent, special, stellar (informal) superior, superlative, well-known
2 arresting, conspicuous, eye-catching, marked, memorable, notable, noteworthy, prominent, salient, signal, striking
3 due, ongoing, open, owing, payable, pending, remaining, uncollected, unpaid, unresolved, unsettled
1 & 2 dull, inferior, insignificant, mediocre, no great shakes (informal) ordinary, pedestrian, run-of-the-mill, unexceptional, unimpressive