IPA: //ʌnˈtʃoʊzən//
KK: /ʌnˈtʃoʊzən/
Not selected or picked; something that has not been chosen.
The unchosen option was left on the table, waiting for someone to decide.
Unchosen → It is formed from "un-" (meaning not) and "chosen" (the past participle of "choose", from Old English "ceosan", meaning to select). The word "unchosen" means not selected or not picked out.
Think of 'not' ('un-') having to do with something that has been 'selected' ('chosen'). This helps you remember that 'unchosen' refers to something that has not been selected.