Steam Is Invisible, and What You See Is Not It
Steam is water in gaseous form. The white cloud from a kettle is not steam but condensed droplets.
Steam is water in its gaseous state, produced by boiling. It is completely invisible. The white plume from a kettle spout is water vapour that has already cooled and condensed back into tiny liquid droplets — look closely and you will see a clear gap between the spout and the visible cloud. That gap is the actual steam. *Let off steam* and *run out of steam* both come from steam engines, where pressure release and pressure loss were literal.
- Water as gas. *A jet of steam.*
- To cook by steam. *Steam the vegetables.*
- Let off steam — release tension. *Let off steam.*
- Run out of steam — lose energy. *Ran out of steam.*
- Old English — *steam*. *The source.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | steam | Steam. |
| Verb | steam | Steam it. |
| Adjective | steamy | Steamy. |
| Compound | steamship | A steamship. |
| Adjective | steaming | Steaming. |
- Steam rose from the kettle.Loosely.
- The visible cloud is condensed water.Physics.
- He let off steam at the gym.Idiom.
Steam engine phrases
- Let off steam — release pressure through a valve
- Run out of steam — lose the pressure driving you
- Under your own steam — moving without being towed
- Full steam ahead — maximum power, from ships
- Steamroller — to flatten opposition, from road machinery
Old English *steam*, vapour or fume, of Germanic origin.
Is steam visible?
No. Steam is a clear gas. The white cloud you see is water vapour that has cooled and condensed into tiny liquid droplets.
Where does let off steam come from?
From steam engines, where a safety valve released excess pressure before it became dangerous.