Incompleteness is the noun: the state of not having everything that should be there, or of not being fully finished. The incompleteness of the data made the study weak. You can feel the incompleteness of a story that stops in the middle. It is a little formal — school, reports, careful talk. Though actually, mathematics borrowed this ordinary word for a deep idea: Gödel’s incompleteness theorems, about what a system of rules can and cannot prove. You do not need that for everyday English. Daily use still means the not-finished, not-all-there quality of something.

不完整、不完全。數學上「不完備」（哥德爾不完備定理）是術語，不是日常說法。