IPA: /ˌɪn.kənˈvɜː.tə.bəl/
KK: /ɪnˈkɒnvɜːtəbl/
Something that cannot be exchanged or converted into another form, especially in terms of currency or value.
The inconvertible currency made it difficult for travelers to exchange their money.
Inconvertible → It is formed from "in-" (meaning not) and "convertible" (from Latin "convertere", meaning to turn around or change). The word describes something that cannot be changed or turned into something else.
Think of 'not' ('in-') being able to 'turn' ('vertere') into something else — that's why inconvertible means something that cannot be changed.