English has hundreds of thousands of compound phrases that name things—not just describe them. “Boiling water” isn’t “water that happens to be boiling.” It’s a hazard, a cooking stage, a state of matter. Yet traditional dictionaries skip almost all of them, because they contain spaces. Merriam-Webster and Oxford cover about 3%.
I got interested in this because I make word games—and wanted to understand which phrases have enough weight to count as vocabulary, and why dictionaries trained us to think they don’t.
Here’s a slider. Look at expressions at different familiarity levels. Gold words are missing from traditional dictionaries:
Crowd-sourced Wiktionary has 16 times more headwords than Merriam-Webster’s already hefty tabletop book. Yet even Wiktionary leaves gaps.