An ambiguity in a writing which will warrant the introduction of parol evidence is duplicity, indistinctness, or an uncertainty of meaning or expression, and mere omission or mistake is not an ambiguity.

Explanation

(English-origin maxim.) Only genuine ambiguity — duplicity, indistinctness, or uncertainty of expression — warrants the introduction of parol evidence; a simple omission or scrivener's error is not ambiguity and does not open the door to extrinsic proof.

Where this applies

• A contract has a typo that leaves out the purchase price, and the buyer wants to introduce testimony about what price was discussed — but a missing price is an omission, not an ambiguity, so parol evidence doesn't come in.
• A deed accidentally omits the lot number, and the buyer tries to bring in oral conversations to fill the gap — the court says that's a scrivener's error, not ambiguity, so the parol evidence rule blocks it.
• A lease contains a clause that could mean either party pays for repairs — that's genuine ambiguity (doubleness of meaning), so the court allows testimony about what the parties actually intended.