Due Diligence
Etymology
Combining "due" (owed or required) with "diligence," from Latin "diligentia" (carefulness, attentiveness), itself from "diligere" (to value or esteem highly) — care rooted in valuing something. It gained specific legal weight from the U.S. Securities Act of 1933, which offered a defense to brokers who had done their "due diligence." From finance it spread to any thorough vetting.
noun phrase · /doo DIL-ih-jents/
The careful investigation of a deal, company, or claim before you commit to it.
What it names
The homework that separates confident decisions from expensive surprises, and makes "we should have checked" inexcusable.
Example
The acquisition looked perfect until due diligence uncovered a pending lawsuit worth millions.
Related idea
Due diligence is the investigation before you sign; a merger or acquisition is what it protects. Skipping it is how buyers inherit hidden debts, and how "information asymmetry" — the seller knowing more than you — quietly costs a fortune.