misconception

mis- +‎ conception or misconceive +‎ -ion

• (US) IPA^(key): /ˌmɪskənˈsɛp.ʃən/

misconception (countable and uncountable, plural misconceptions)

1. a mistaken belief, a wrong idea

   There are several common misconceptions about the theory of relativity.

   You're obviously under the misconception that I care about your problems.

   He thought that a misconception meant becoming pregnant with a girl.

• conceptionism