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”
    below the required standards for a purpose
  2. adjective
    not worthy of being chosen (especially as a spouse)
    synonyms: undesirable
    not eligible
  3. adjective
    not conducive to good moral development
    “the movie is unsuitable for children”
    having undesirable or negative qualities
  4. adjective
    not capable of being applied
    synonyms: inapplicable
    having no bearing on or connection with the subject at issue
Word Family