also: うわじき
noun
A mat or rug placed on top of tatami, flooring, or another surface; often refers to a bordered mat or a small carpet.
座卓の下に上敷きを敷いた。
I put a rug under the low table.
この上敷きは縁が補強してあって丈夫だ。
This mat has reinforced edges and is durable.
noun
saddlecloth; harness
Archaic term for a cloth placed under a saddle or for horse harness; not used in modern everyday language.
古文書には、馬に上敷きをかける記述がある。
In old documents, there is a description of putting a saddlecloth on a horse.
Abbreviated spelling; less common but still seen.
Alternate reading with abbreviated spelling; rarely used.
敷物 is a general term for any floor covering (rug, carpet, mat), while 上敷き specifically implies something placed on top of another surface, often with a border.
カーペット is a loanword for carpet, typically wall-to-wall or large area rugs, whereas 上敷き is a more traditional Japanese term for a smaller mat or rug.
Compound of 上 (うわ, 'upper') + 敷き (しき, 'spreading'), literally 'spreading on top'. The exact historical derivation is uncertain, but the word has been used since at least the Edo period for mats and saddlecloths.