A horizontal structural member, such as a beam or stone, that spans an opening, as between the uprights of a door or window or between two columns or piers.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "lintel" in a sentence
"The word isn't lintel, which is the horizontal top of a doorway."
"The principal item is the upper cave, small, square, and apparently still used by the Arabs: in the middle of the lintel is a lump looking like the mutilated capital of a column."
"Fig. 98: Make sure the lintel is the correct size for wide openings."