IPA: /ˌɪndɪˈskraɪbəl/
KK: /ɪnˈdɛskrɪbəl/
Something that is so amazing, strange, or extreme that it cannot be described in words.
The beauty of the sunset was indescribable, leaving everyone speechless.
Indescribable → It is formed from "in-" (meaning not) and "describere" (meaning to write down or describe) and the suffix "-able" (meaning capable of). The word "indescribable" means not capable of being described, often due to its extraordinary nature.
Think of something that is 'not' ('in-') able to be 'described' ('describere') — that's why we call it indescribable.