locknut vs safety nut

locknut and safety nut both are nouns.

Word	Noun	Adjective	Verb	Adverb
locknut	Yes	No	No	No
safety nut	Yes	No	No	No

As nouns, locknut and safety nut are synonyms defined as:

locknut and safety nut: supplementary nut that is screwed down on a primary nut to prevent it from loosening

locknut (noun)	safety nut (noun)
supplementary nut that is screwed down on a primary nut to prevent it from loosening	supplementary nut that is screwed down on a primary nut to prevent it from loosening