“Keep Your Options Open” means to delay a final choice so that different possibilities remain available. The guide stays with current documented meaning and does not add unsupported origin chronology.
“Put your money where your mouth is” means to show through actions—not only words—that you genuinely support or believe in something. This guide limits itself to the documented current meaning.
“At stake” means that something valuable is in danger of being lost. The guide stays with current documented meaning and does not add unsupported origin chronology.
A “black swan” is an event that happens despite people having thought it could not happen. Use the figurative sense for a supposedly impossible or profoundly unexpected event; keep it distinct from the literal black swan bird, and do not treat every ordinary surprise as a black swan.
The butterfly effect describes disproportionate downstream consequences from a small change. Cambridge connects the phrase with chaos theory; in general use, keep the emphasis on a small initial change producing a much larger outcome rather than on ordinary direct causation.
Oxford defines “a canary in a/the coal mine” as something that gives an early warning of danger. This guide uses that current figurative meaning without claiming an unsupported exact first use.
A “chain reaction” describes a series of events in which each event causes the next one. In figurative use, focus on the causal sequence; the expression also has a literal scientific sense, so context determines which reading applies.
In figurative and business use, critical mass is a threshold: enough people, customers, resources or scale for a development to become possible or self-sustaining. Context separates that use from the literal physics meaning.
