Origin and history of steam

Middle English stēm, from Old English steam "vapor from a body, fumes, a scent or odor given off from a heated or burned object," from Proto-Germanic *staumaz (source also of Dutch stoom "steam"), a word of unknown origin.

The meaning "water in a gaseous state" is from mid-15c. Especially "vapor of boiling water used to drive an engine" from 1690s. Hence many figurative uses, such as let off steam (1783 in a literal sense; figurative by 1845 ("Sam Slick")), blow off steam (1857 figurative), full-steam (1812 literal), get up steam (1887 figurative).

Hence also Steam Age (1828, at the start of it) in reference to the era when steam power predominated.

We have given her six months to consider the matter, and in this steam age of the world, no woman ought to require a longer time to make up her mind. [Sarah Josepha Hale, "Sketches of American Character," 1828]

But by 1941 it meant "old-fashioned." Steam heat is by 1824 in thermodynamics, "heat required to produce steam;" from 1901 as a method of temperature control involving condensation of steam in pipes or radiators.

Old English stiemen, stymen "emit vapor, emit a scent or odor," from the root of steam (n.). Meaning "go by steam power" is from 1831. Transitive sense from 1660s, "to emit as steam;" meaning "to treat with steam" is from 1798. Slang steam up (transitive) "make (someone) angry" is by 1921, American English; steamed up is attested slightly earlier in slang as "motivated, enthused" (1913). Related: Steamed; steaming.