adv. phr. , informal By one's own efforts; without help. The boys got to Boston under their own steam and took a bus the rest of the way. We didn't think he could do it, but Bobby finished his homework under his own steam.
UNDER ONE'S OWN STEAM
Meaning of UNDER ONE'S OWN STEAM in English
American idioms English vocabulary. Английский словарь американских идиом. 2012