vapor, steam
汽 centers on gaseous water: vapor or steam, the visible mist that rises from hot water.
汽 combines 氵 (water) and 气 (air/steam), suggesting water turning into vapor or steam.
Water 氵 meets air 气 and rises as steam: 汽 is vapor.
For キ, imagine a key turning in a steam engine, releasing a hiss of vapor: key -> キ.
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train (esp. a long-distance train)
steam whistle
steamship; steamboat; steamer
brackish water
night train
Katou Kisen
Nihonkai Steamship Co. Ltd.
steam power
steam pressure
brackish waters (of an estuary)
brackish lake
boiler
boiler room
shipment by steamer
(steam) launch
choo-choo train
train fare
Parafontaria laminata (species of millipede)
steam pot chicken (Yunnan cuisine)
Kansai Kisen