late 14c., from Late Latin indeterminatus "undefined, unlimited," from in- "not, opposite of" (see in- (1)) + determinatus, past participle of determinare "to enclose, bound, set limits to" (see determine). Related: Indeterminately.
word-forming element making nouns of quality, state, or condition, a confusion in English of three similar suffixes from Latin:
1. in primacy, etc., from Old French -acie and directly from Medieval Latin -acia, Late Latin -atia, making nouns of quality, state, or condition from nouns in -as.
2. in advocacy, etc., from Late Latin -atia, forming nouns of state from nouns in -atus.
3. in fallacy, etc., from Latin -acia, forming nouns of quality from adjectives in -ax (genitive -acis). Also forming part of -cracy. It has been extended in English to nouns not found in Latin (accuracy) and to non-Latin words (piracy).
<a href="https://www.etymonline.com/word/indeterminacy">Etymology of indeterminacy by etymonline</a>
Harper, D. (n.d.). Etymology of indeterminacy. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/indeterminacy