IPA: /ˌɪn.dɪˈfaɪ.nə.bəl/
KK: /ɪndɪˈfaɪnəbl/
Something that cannot be clearly defined or described.
The beauty of the sunset was indefinable, leaving everyone speechless.
A person or thing that cannot be clearly defined or described.
The concept of love can sometimes feel like an indefinable experience.
Indefinable → It is formed from "in-" (meaning not), "definire" (from Latin, meaning to define), and "-able" (meaning capable of). The word "indefinable" means not capable of being defined or described clearly.
Think of 'not' ('in-') being able to 'define' something ('definire') — that's why indefinable means something that cannot be clearly defined.