Any of the wood, steel, or concrete beams set parallel from wall to wall or across or abutting girders to support a floor or ceiling.
tr.v. joist·ed, joist·ing, joists
To construct with joists.
[Middle English giste, joiste, from Old French giste, from feminine past participle of gesir, to lie, lie down, from Latin iacēre; see yē- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.