IPA: /nɒnˈrɪəˌlɪstɪk/
KK: /nɑnˈriːəlɪstɪk/
Not based on reality or not representing things as they truly are; often used to describe ideas, plans, or representations that are fanciful or impractical.
The movie was filled with nonrealistic scenarios that made it hard to believe.
Nonrealistic → It is formed from "non-" (meaning not) and "realistic" (from Latin "realis", meaning actual or real, combined with the suffix "-istic", meaning pertaining to). The word "nonrealistic" means not pertaining to or not resembling reality.
Think of 'not' ('non-') and 'real' ('realis') to remember that 'nonrealistic' describes something that does not resemble reality.