unconvincing

/ˈʌnkənˌvɪnsɪŋ/

Anything that's unconvincing is unlikely or hard to believe. Your unconvincing story about being abducted by aliens probably won't persuade your teacher to give you an extension on your term paper.

Your unconvincing impersonation of President Ronald Reagan might sound more like John Wayne, and an unconvincing alibi won't get a suspect off the hook if a detective thinks she's guilty. The adjective unconvincing comes from convince, "cause to believe in the truth of something," and its root that means "to conquer." If you haven't convinced someone of some fact or truth, you've been unconvincing.

Definitions of unconvincing

1. adjective

   not convincing
   “unconvincing argument”

   “as unconvincing as a forced smile”

   synonyms: flimsy

   unpersuasive

   not capable of persuading

   incredible, unbelievable

   beyond belief or understanding

   antonyms:

   convincing

   causing one to believe the truth of something

   credible

   appearing to merit belief or acceptance

   disenchanting, disillusioning

   freeing from illusion or false belief

   persuasive

   intended or having the power to induce action or belief
2. adjective

   having a probability too low to inspire belief
   synonyms: improbable, unbelievable, unlikely

   implausible

   having a quality that provokes disbelief