IPA: //ʌnˈspɛsɪfaɪə//
KK: /ʌnˈspɛsɪfaɪə/
Not able to be clearly defined or described.
The details of the project were unspecifiable at this stage.
Unspeficable → It is formed from "un-" (meaning not), "speci-" (from Latin "specere", meaning to look or see), and "-fiable" (from Latin "facere", meaning to make). The word "unspecifiable" means something that cannot be clearly defined or made specific.
Think of something that cannot be 'made specific' — 'un-' means not, 'speci-' relates to looking or seeing, and '-fiable' means to make.