grout

UK: /ˈgraʊt/ US: (grout)

WordReference Random House Unabridged Dictionary of American English © 2025

grout  (grout), n. 

1. a thin, coarse mortar poured into various narrow cavities, as masonry joints or rock fissures, to fill them and consolidate the adjoining objects into a solid mass.
2. a coat of plaster for finishing a ceiling or interior wall.
3. Usually, grouts. lees;
   grounds.
4. [Archaic.]
   • coarse meal or porridge.
   • grouts, groats.

v.t. 

5. to fill or consolidate with grout.
6. to use as grout.

• bef. 1150; Middle English; Old English grūt; see grits, groats, grit

grout′er, n. 

Collins Concise English Dictionary © HarperCollins Publishers::

grout / ɡraʊt/ noun

1. a thin mortar for filling joints between tiles, masonry, etc
2. a fine plaster used as a finishing coat

verb

1. (transitive) to fill (joints) or finish (walls, etc) with grout

Etymology: Old English grūt; related to Old Frisian grēt sand, Middle High German grūz, Middle Dutch grūte coarse meal; see grit, groats

ˈgrouter noun