also: き
counter for small animals
Only with reading ひき
Used to count small animals such as cats, dogs, fish, insects, and similar creatures. Larger animals are more often counted with 頭. The pronunciation changes after some numbers: 一匹 is いっぴき, 二匹 is にひき, 三匹 is さんびき.
We keep two cats at home.
There were three small fish in the pond.
counter for rolls of cloth
Traditional or specialized textile use for counting rolls of cloth, described as rolls of cloth of two han in size. This is not an everyday counter for learners outside historical, textile, or kimono-related contexts.
In old books on Japanese sewing, bolts of cloth are counted as one hiki, two hiki.
archaic counter for horses
Only with reading き
Archaic use read き for counting horses. In modern Japanese, horses are normally counted with 頭, while 騎 is used in contexts such as mounted riders or cavalry.
In old annotations, the use of 匹 read as ki for counting horses is explained.
roll of cloth
Noun use meaning a roll of cloth. This is a traditional textile term and is rare in ordinary modern conversation compared with clearer words such as 反物.
In old textile materials, 疋 sometimes appears as a noun referring to a roll of cloth.
There were three cats in the park.
匹 is the general counter for small animals, but 羽 is the conventional counter for birds (and often rabbits).
Less common variant spelling, more likely in older, traditional, or textile-related contexts than in ordinary modern writing.
Archaic variant spelling-reading combination for the horse-counter sense, included mainly for recognizing older texts.
Kana spelling is practical in learner-facing or casual writing for the small-animal counter, though the kanji 匹 is the standard dictionary form.