Definition, synonyms and related words
simple past tense and past participle of fail
"The experiment failed after hours of trying to replicate the results."
In plain English: To fail means to try something and not succeed at it.
"The test failed to detect the virus in his sample."
Usage: Use "failed" to describe an action that did not succeed in the past or to state that someone has previously been unsuccessful. It functions as both the simple past tense and the past participle of the verb "fail."
unsuccessful
"After hours of trying to climb the slippery rocks, we finally failed and had to turn back."
In plain English: Failed means something did not work or succeed as planned.
"The failed attempt to start the car left us stranded in the rain."
Usage: Use "failed" as an adjective only when describing something that has specifically failed to function or operate, such as a battery or a system. Do not use it to describe general lack of success, where "unsuccessful" is the correct choice.
Derived from Old French faillir meaning "to fail" or "lack," it entered English in the late 14th century with the original sense of falling short of an expected standard. The past tense form retains this core definition while also implying a lack of success in achieving a goal.