False Negative
Etymology
“Negative” is from Latin “negativus,” from negare (to deny); a “negative” result denies the condition is present. As with its counterpart, the diagnostic pairing comes from medicine and signal-detection theory.
noun phrase · /FAWLS NEG-uh-tiv/
A test result that wrongly signals all is clear when the condition is actually present.
What it names
The miss that reassures you falsely — often the more dangerous of the two possible errors.
Example
A cancer screen that returns a false negative sends a sick patient home believing they are healthy.
Related idea
Reducing false negatives usually means accepting more false positives, and vice versa — the unavoidable trade-off that sensitivity and specificity put into numbers.