1. A generally hard, strong, durable, malleable alloy of iron and carbon, usually containing between 0.2 and 1.5 percent carbon, often with other constituents such as manganese, chromium, nickel, molybdenum, copper, tungsten, cobalt, or silicon, depending on the desired alloy properties, and widely used as a structural material.
2. Something, such as a sword, that is made of steel.
3. A quality suggestive of this alloy, especially a hard, unflinching character.
4. Steel gray.

1. 1. Made with, relating to, or consisting of steel: steel beams; the steel industry; a bicycle with a steel frame.
   2. Very firm or strong: a steel grip.
2. Of a steel gray.

1. To cover, plate, edge, or point with steel.
2. To make hard, strong, or obdurate; strengthen: He steeled himself for disappointment.

[Middle English stel, from Old English stȳle, stēl.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.