Wiktionary
false negative
n. 1 A result of a test that shows as absent something that is present. 2 (context statistics English) type II error
Usage examples of "false negative".
Michaels emphasized anew that at this juncture of their work, eliminating false negative readings was the most important task.
Which means that instead of having one true reading and three false positives, the tests resulted in three true readings and one false negative.