IPA: /ʌnˈtʃeɪnd/
KK: /ʌnˈtʃeɪnd/
Not tied down or restricted by chains; able to move freely.
After years of captivity, the horse was finally unchained and could run freely in the field.
Unchained → It is formed from "un-" (meaning not) and "chained" (from the Old English "cæne", meaning to bind or fasten). The word "unchained" means not bound or freed from chains.
Think of being 'not' ('un-') 'bound' ('chained') — that's why unchained means free from chains.