noun
unfinished manuscript; draft
Refers to a manuscript or written work that is not yet finalized; often used in academic or publishing contexts.
彼の未定稿が机の上に積まれている。
His unfinished manuscripts are piled up on the desk.
原稿 is a general term for a manuscript, which may be finished or unfinished; 未定稿 specifically means it is not yet complete.
Compound of 未 (not yet) + 定稿 (finalized manuscript). The exact historical derivation is uncertain, but the components transparently convey the meaning.