1 unusual, different, atypical, eccentric, extraordinary, remarkable, special, uncommon, strange, odd, peculiar, bizarre, outlandish, curious, queer, outré, offbeat, Slang far-out:
Ideas that yesterday were considered singular have today become quite commonplace
2 outstanding, prominent, eminent, pre-eminent, noteworthy, significant, important, conspicuous, particular, notable, signal, exceptional, superior:
Stempel made a singular contribution to the development of microscopy.
3 lone, isolated, single, separate, uncommon, rare, unique, distinct, one of a kind:
Some medieval philosophers denied the existence of general realities, and claimed that all things that exist were particular and singular.