"sheet of backing material," 1845, from French mat "dull surface or finish" (15c.), noun use of Old French mat (adj.) "dull, beaten down," for which see mat (adj.). The word has been confused with mat (n.1), especially as the latter was used late 19c. for "piece of thick paper or other material placed for ornament or protection immediately under the glass of a picture-frame, with the central part cut out, for the proper display of the picture." As a verb, "to mount (a print) on a cardboard backing," by 1965. Related: Matted; matting.

early 15c., matten, "to make mats," from mat (n.1). From 1540s as "to provide with mats, to cover with mats;" meaning "to become tangled" is from 1570s. Related: Matted; matting.

"an article plaited or woven of more or less coarse natural materials (rushes, straw, twine, etc.) used as bedding, floor-coverings, etc.," Old English matte, from Late Latin matta "mat made of rushes" (4c.), probably from Punic or Phoenician matta (compare Hebrew mittah "bed, couch").

Meaning "tangled mass; anything closely set, dense, and thick" is from 1835. Meaning "thin, flat article to be placed under a dish, plate, etc. to protect the table" is by 1800. That of "piece of padded flooring used in gymnastics or wrestling" is attested from 1892; hence figurative phrase go to the mat "do battle" (1910). The Latin word also is the source of German Matte, matze; Dutch mat, Italian matta. French natte "mat, matting" is from Late Latin secondary form natta (compare napkin).

1640s, "lusterless, dull" (of a color or surface), from French mat "dull, dead surface," from Old French mat "beaten down, withered, afflicted, dejected; dull," which is perhaps from Latin mattus "maudlin with drink," from madere "to be wet or sodden, be drunk," from PIE root *mad- "to be wet, drip" (see mast (n.2)). Or the French word might represent a transferred use from chess of mater "to checkmate, defeat," from Arabic (see mate (v.2)).

"table-mat for a place, setting," by 1949, from place (n.) + mat (n.).

also doormat, "heavy mat placed before a door for use in cleaning the shoes by those entering," 1660s, from door + mat. Figurative use in reference to persons people "walk all over" or upon whom they (figuratively) clean their boots is by 1861.

"backing for a picture," 1845, from French; see mat (n.2).

"ornamental border of a picture," 1864 from verbal derivative of mat (n.2).

"tangled and lying flat" (of hair, vegetation, fibers, etc.), 1610s, past-participle adjective from mat (v.).

"process of making mats," 1720, from mat (n.1). Meaning "fabric of coarse material for mats" is from 1748.