IPA: //ʌnˈsɪkjʊrd//
KK: /ʌnˈsɪkjʊrd/
Not fastened or attached; in finance, it refers to a loan that does not have collateral backing it.
He took out an unsecured loan to pay for his education.
Unsecured → It is formed from "un-" (meaning not) and "secure" (from Latin "securus", meaning free from care or safe). The word "unsecured" means not safe or not protected.
Think of 'not' ('un-') being added to 'safe' ('secure') — that's why unsecured means something that is not safe.