absque

Absque is ab plus the enclitic -que, and it governs the ablative. In classical prose it is rare and specialised: Plautus and Terence use it in a conditional idiom, absque te esset, "had it not been for you", and Cicero barely touches it. Sine is the ordinary classical word for "without".

Late and medieval Latin changed that. Absque spread until it was simply a heavier alternative to sine, and in charters, chronicles and scholastic prose it is common. Absque dubio sits alongside sine dubio with no difference in meaning. So the trap runs backwards from the usual one: if you are writing classical Latin, reach for sine; if you are reading a medieval text, do not read anything special into absque.