inadequate

not good enough

incurable

not able to be healed of an illness, untreatable

inactive

not involving much physical activity

incomplete

not having all the necessary parts, not finished

insecure

not confident or assured, uncertain or anxious; OR easily broken (unprotected)

invisible

unable to be seen

inelegant

not showing grace or refinement, clumsy, ungraceful

inflexible

not willing to change or compromise (stubborn); OR not able to bend (rigid)

inability

the state of being not capable of doing something

indefinite

lasting for an unknown length of time

insane

not in a normal state of mind, crazy

independent

not relying on another person to take care of your needs

invalid

not founded in truth or logic

involuntary

done without your control (like a sneeze)

insignificant

not important

inexpensive

does not cost a lot