Glossary
Plain-language definitions of every term the product uses — score, match, passage, source, corpus, fingerprint, and more.
Check
One run of a document through the engine. A check consumes one unit of your plan's monthly allowance and produces a report. Checks stay in your history until you delete them.
Similarity score
The percentage of your text that overlaps with known sources — the deduplicated union of all matched passages. A measure of textual overlap, not a verdict. See Understanding your similarity score.
Match
An overlap the engine found between a passage of your text and a passage of a source, with exact character positions on both sides.
Passage
A contiguous span of your text that matched one or more sources. In the report, passages are the highlighted regions; clicking one shows which sources it matched.
Source
A document your text matched: a web page, an indexed document, or a document from the Noplag Database or your folders. Each source has its own match percentage and passage list.
Corpus
A body of documents the engine compares against. Noplag checks run against several corpora: a large web snapshot, Wikipedia, academic sources, the Noplag Database — and, on Premium, the live web.
Live-web layer
The Premium feature that searches the live web at check time and fetches candidate pages fresh, covering content newer than the indexed corpus. See The live-web layer.
Noplag Database
The corpus built from documents submitted for checking. It protects submitted work: if someone later checks text copied from your document, it matches — anonymously. Opt-out, on by default. See The Noplag Database.
Fingerprint
The compact numeric representation the engine stores instead of raw text for matching (winnowing fingerprints). Two texts that share verbatim content share fingerprints; the fingerprints alone can't reconstruct the original document. The technique is documented in the open-source engine.
Match sensitivity
The report filters that exclude short matches (5/8/10/15-word thresholds) and quoted text from the score. See Match sensitivity.
Coverage
Whether the whole document was checked. Very large documents can hit the per-check time budget; the report then says coverage was partial rather than pretending the scan was complete.
Folder
A grouping for checks in your workspace — by client, course, or project. See Folders.
Share link
A read-only public link to a report, optionally password-protected, revocable at any time. See Sharing reports.
Live / test API key
Keys for the Noplag API (Pro and Premium). Live keys run real, billed checks; test keys run the full pipeline without persisting, billing, or counting toward quota. See API keys.