noun
woven mat; sedge mat; straw mat
A mat woven from plant materials such as sedge or hay, used for covering, sitting, or drying things.
漁師は船の上で苫を敷いて休んだ。
The fisherman spread a woven mat on the boat and rested.
昔の家では、苫を屋根に使うこともあった。
In old houses, woven mats were sometimes used on roofs.
ござ is a thinner mat, often made of rush, used as a floor covering or for sitting, while 苫 is coarser and used for more utilitarian purposes like covering cargo or drying grain.
むしろ is a general term for a coarse woven straw mat, similar to 苫, but 苫 often implies a mat made of sedge or used in specific contexts like boats or roofs.
The word とま is of native Japanese origin. The kanji 苫 is a phono-semantic compound with 艹 (plant) and 占 (to occupy), suggesting a mat that covers or occupies a space. The alternate kanji 篷 originally referred to a bamboo mat or awning, and its use for とま is an extension.