unsuitable

/ˈʌnˌsudəbəl/

/ənˈsutəbəl/

Something that's unsuitable doesn't work well or is out of place. A kitchen knife is unsuitable for sawing firewood.

You can use the adjective unsuitable to describe something that isn't well suited for a use: flip flops are unsuitable shoes to wear in a blizzard. It's also a good word for something that's disappointing or undesirable: "No, that guy in the clown suit would be a completely unsuitable boyfriend for me." At the root of unsuitable is the meaning of suit, "be agreeable or convenient," that's thought to come from "provide a suit of clothes."

Definitions of unsuitable

1. adjective

   not meant or adapted for a particular purpose
   “a solvent unsuitable for use on wood surfaces”

   synonyms:

   unfit

   below the required standards for a purpose
2. adjective

   not worthy of being chosen (especially as a spouse)
   synonyms: undesirable

   ineligible

   not eligible
3. adjective

   not conducive to good moral development
   “the movie is unsuitable for children”

   synonyms:

   bad

   having undesirable or negative qualities
4. adjective

   not capable of being applied
   synonyms: inapplicable

   irrelevant

   having no bearing on or connection with the subject at issue