The twins' voices were undistinguishable over the phone, so their mother couldn't tell which child was calling.

The undistinguishableness of the two paintings frustrated the art students, who spent hours searching for subtle differences.

The undistinguishability of the two samples under the microscope made it difficult to determine their origin.

Her undistinguishing summary of the cases overlooked crucial differences that affected the verdicts.

The two twins dressed identically and answered the questions undistinguishably during the interview, leaving the panel unsure which was which.

The committee overlooked his undistinguished proposal in favor of more ambitious projects.