1steam 
/ˈsti:m/ noun
/ˈsti:m/ noun [noncount] 1 a : the hot gas that is created when water is boiled
▪ Careful, the steam from the pot is hot.
b : steam that is created by a machine and kept under pressure to provide power
▪ Steam drives the turbines. ▪ a steam-powered engine ▪ The boat runs on steam. — often used before another noun ▪ a steam engine/train 2 : very small drops of water that form on a surface when warm air that contains a lot of water is cooled down
▪ He wiped the steam from the mirrors. 3 informal : the strength, force, or energy that allows something or someone to continue, to go faster, etc.
▪ Sales have lost steam [=have slowed down] in recent weeks. ▪ The campaign quickly gained/gathered steam. [=became more popular and successful] ▪ He was afraid he would run out of steam before the end of the race. ▪ I was making good progress this morning, but now I'm starting to run out of steam. ▪ The project is slowly picking up steam. [=slowly beginning to move ahead in a faster and more effective way]
▪ Careful, the steam from the pot is hot.
b : steam that is created by a machine and kept under pressure to provide power
▪ Steam drives the turbines. ▪ a steam-powered engine ▪ The boat runs on steam. — often used before another noun ▪ a steam engine/train
▪ He wiped the steam from the mirrors.
▪ Sales have lost steam [=have slowed down] in recent weeks. ▪ The campaign quickly gained/gathered steam. [=became more popular and successful] ▪ He was afraid he would run out of steam before the end of the race. ▪ I was making good progress this morning, but now I'm starting to run out of steam. ▪ The project is slowly picking up steam. [=slowly beginning to move ahead in a faster and more effective way]
full head of steam — see 1head
full steam ahead — see 1full
let/blow off (some) steam
informal : to calm down and get rid of energy or anger by doing something active
▪ I play racquetball every evening just to let off some steam. ▪ Tell him to go blow off some steam and then we can talk.
▪ I play racquetball every evening just to let off some steam. ▪ Tell him to go blow off some steam and then we can talk.
under its own steam
of a ship, boat, etc. : by using its own power
▪ The ship was damaged but was able to return to port under its own steam. — often used figuratively ▪ He got there under his own steam. [=by himself; by his own efforts]
▪ The ship was damaged but was able to return to port under its own steam. — often used figuratively ▪ He got there under his own steam. [=by himself; by his own efforts]
