IPA: /ˌɪndɪˈkoʊmpəbl/
KK: /ɪnˌdiːkəmˈpoʊzəbl/
Something that cannot be divided into smaller parts or components.
The scientist studied indecomposable matter to understand its properties.
Indecomposable → It is formed from "in-" (meaning not), "decomponere" (from Latin, meaning to separate or break down), and "-able" (meaning capable of). The word "indecomposable" means not capable of being separated or broken down into simpler parts.
Think of 'not' ('in-') being able to 'break down' ('decomponere') something — that's why indecomposable means it cannot be separated.