IPA: /ʌnˈrɛkəɡnaɪzəbl/
KK: /ʌnˈrɛkəɡnaɪzəbl/
Something that cannot be identified or recognized, often due to significant changes in appearance or characteristics.
After the renovation, the old building looked unrecognizable.
Unrecognizable → It is formed from "un-" (meaning not) and "recognize" (from Latin "recognoscere", where "re-" means again and "cognoscere" means to know). The word means not able to be known again or not able to be identified.
Think of 'not' ('un-') being added to 'know again' ('recognize') — that’s why unrecognizable means something that cannot be identified.