While uncomplete simply means something that was never completed.for example a house under construction(not renovation) and its not yet finished is said to be uncompleted because it was never complete.

What does uncompleted mean?

: not brought to an end or to the desired final state : not completed an uncompleted portrait/project an uncompleted crossword puzzle.

Is uncompleted correct?

Incomplete means (and meant) that not all parts are present. The Latin negative in- prefix was already attached, before the word was borrowed. The opposite of uncompleted is completed; i.e, finished, done (of activities). Completed is the past participle of the English verb complete, not a Latin verb.