joist

noun

ˈjȯist 

: any of the small timbers or metal beams ranged parallel from wall to wall in a structure to support a floor or ceiling

Illustration of joist

• J joist

Examples of joist in a Sentence

Recent Examples on the Web

To fix this, homeowners can use spray foam or rigid foam board to seal the gaps and stop the flow of cold air from flowing over the floor joists and into the living space. —Ashlyn Needham, Southern Living, 22 Jan. 2026

These 2×8 floor joists can create a floor that resembles a trampoline, and still be code-compliant. —Tim Carter, Hartford Courant, 3 Jan. 2026

Insulation that fills to the top of the joists is about R21. —Sarah Moore, Freep.com, 12 Dec. 2025

Various hovering white forms, testing the match of simulation to dimly seen reality, offered my ghostly virtual hand the opportunity to pull the white virtual door off its joists, or to detach the virtual window from the actual one looking out onto Lower Manhattan. —Caroline A. Jones, Artforum, 1 Nov. 2025

Word History

Etymology

Middle English giste, joiste, from Anglo-French giste, from Vulgar Latin *jacitum, from Latin jacēre to lie — more at adjacent

First Known Use

15th century, in the meaning defined above

Rhymes for joist

• foist
• hoist
• moist
• voiced
• rejoiced
• unvoiced

Kids Definition

joist

noun

ˈjȯist 

: a small beam laid crosswise to support a floor or ceiling